CN101876691B - System and method for testing magnetoelectricity property of multiferroic thin-film material - Google Patents

Abstract

The invention relates to a system and a method for testing magnetoelectricity property of a multiferroic thin-film material, belonging to the field of property tests of materials. The system is characterized by comprising a DC bias magnetic field generating device, an AC magnetic field generating device, a thin-film sample probe holding device and a micro signal acquiring and amplifying device. The invention also provides a method for testing magnetoelectricity property of the multiferroic thin-film material. The invention can recognize the difference of an electromagnetic inductive interference signal and a multiferroic magnetoelectricity responding signal by accurately testing a thin-film micro electric responding signal so as to obtain a real amplitude of a magnetoelectricity coefficient of the multiferroic thin-film material under different frequencies and bias magnetic fields and also obtain the change law of thin-film sample polarization with a sine magnetic field.

Description

The magnetic electricity performance test macro and the method for testing thereof of multiferroic film material

Technical field

The present invention relates to a kind of instrument and method of testing of measuring the magnetic electricity performance of multiferroic film material, belong to the performance test field of material.

Background technology

The multiferroic film material possesses multiferroics such as ferroelectric, ferromagnetic simultaneously, has magnetic and electric coupling response, is a kind of material system with wide application prospect compatible with microelectronic technique.In the multiferroic film material; Magnetoelectric effect is one of its topmost physical influence; Magnetic electricity performance can be weighed and representes through magnetoelectricity voltage coefficient or mangneto electric polarization, and its Changing Pattern with frequency, magnetic field then is important analysis means of understanding magneto-electric coupled mechanism of multi-ferroic material and efficient.The multiferroic film material is divided into single-phase multiferroic film material and many iron property magnetoelectricity laminated film two big classes substantially; Wherein the former can cause the coupling of material magnetic domain and electricdomain under bigger sinusoidal magnetic field effect; Produce electric polarization, and the latter is because stress induced machining function just can produce different big or small electric fields by certain perturbation sinusoidal magnetic field under certain bias magnetic field; Because its mechanism of action is different, use different means of testing to carry out analysis and characterization with regard to needing.And the capable membraneous material of many iron all has a wide range of applications in sensing, driving, storage and intelligence system, receives researchist's extensive concern.

The present nobody of magnetic electricity performance tester who is directed to membraneous material carried out report and open; And for the analytical test aspect of magnetoelectricity block materials; (Bracks.L.P.M.and van Vliet.R.G.A broadband magneto-electric transducer using a composite material.International Journal of Electronics.1981 discloses a kind of magnetic-electric coefficient proving installation in 51:225) to people such as Bracks in 1981 at paper.This device applies the direct current biasing magnetic field H with permanent magnet _DCDrive helmholtz coil with signal generator and produce sinusoidal perturbation magnetic field H _AcBe connected with magnetoelectric material with impedance transformer, measure the voltage of magnetoelectric material.2004; People such as the Dong of the U.S. are at his paper (Dong S.X.; Li J.F.and V iehland D.Characterization of magnetoelectric laminate composites operated in longitudinal-transverse and transverse-transverse modes.Journal of Applied Physics.2004 discloses his proving installation in 95:2625).Wherein, adopt the direct supply drive magnetic to produce direct current biasing magnetic field; Adopt sinusoidal voltage of lock-in amplifier output, amplify through AC power amplifier, drive helmholtz coil and produce sinusoidal perturbation magnetic field, lock-in amplifier also is used to measure the output voltage of magnetoelectric material simultaneously.This device can specimen magnetic-electric coefficient under or parallel two kinds of angles vertical with magnetic field.2006; People such as Tsing-Hua University puts to good use, Nan Cewen apply for a patent the proving installation that discloses the magnetoelectricity block materials, and wherein emphasis has solved that magnetic-electric coefficient phase test problem, material output voltage are gone between and the problem of the capacitive effect of tester, test angle continually varying problem and the problem of being carried out automatic measurement by software control.

The deficiency that present measuring technology exists has: present test macro because the response signal value of membraneous material is far smaller than block materials (three one magnitude extremely when young), can't accurately be measured response signal all towards block materials; Because a little less than the membraneous material signal, electromagnetic induction interference is strong, can't get rid of the influence of electromagnetic interference (EMI) to test; Because membraneous material film upper surface electrode is little and thin, general lead-in wire test technology can produce damaging influence to sample at present, can't carry out lossless detection to sample; Because the magneto-electric coupled mechanism of dissimilar multiferroic film materials is different, can't select method of testing to test targetedly.

Summary of the invention

The magnetic electricity performance test macro and the corresponding test method that the purpose of this invention is to provide a kind of multiferroic film material; This test macro is the magneto-electric response signal of MEASUREMENTS OF THIN material accurately; Get rid of the interference electromotive force that electromagnetic induction produces; Simultaneously can also carry out lossless detection, need not to go between sample; Four kinds of magnetic electricity performance method of testings based on this tester are provided on the other hand, can have tested to dissimilar multiferroic film materials respectively.

The present invention compared with prior art has the following advantages and the high-lighting effect:

Present invention is directed to the magnetic electricity performance test macro of multiferroic film material; Can carry out accurate small electric response signal surveys; Can get rid of the influence that interference electromotive force that electromagnetic induction causes causes test, can carry out the repetition lossless detection, provide simultaneously to have comprised D.C. magnetic field H sample _DC, AC magnetic field H _Ac, three kinds of frequency f test changing factor respectively to four kinds of magnetic electricity performance measuring methods of dissimilar multiferroic film materials.The present invention contains the sample probe clamping device makes sample can use the probe method of clamping to survey the electroresponse signal, need not lead-in wire; The present invention contains bipolar power supply; Can drive helmholtz coil provide near or surpass the sinusoidal magnetic field of ferromagnetic thin film material saturation magnetic fields such as single-phase multiferroic film material such as ferrous acid bismuth or nickel ferrite based magnetic loaded, for the magneto-electric coupled performance testing of these materials provides possibility; The step method that the present invention contains the device of finely tuning sample angle and provides undesired signal to get rid of criterion has been eliminated because the influence of the induced electromotive force that lead-in wire and probe current loop area bring.

Description of drawings

The circuit side connector block diagram of Fig. 1 test macro.

Fig. 2 film sample probe to be measured clamping device synoptic diagram.

Assembling of Fig. 3 spring probe and rotation synoptic diagram.

Fig. 4 instance one 120 nano lead zirconate titanates and 80 nano-ferrous acid laminated film samples are at test frequency f=1000Hz, sinusoidal magnetic field H _AcMagnetic-electric coefficient is with direct current biasing changes of magnetic field graph of a relation under the condition of=134Oe.

Fig. 5 instance 2 96 nano barium phthalates and 24 nano nickel ferrite laminated film samples are at sinusoidal magnetic field H _AcMagnetic-electric coefficient is with sinusoidal magnetic field frequency f variation relation figure under=86Oe, the no direct current biasing magnetic field.

The single-phase film sample of Fig. 6 instance 3 300 nanometer ferrous acid bismuths is at no bias magnetic field, the test frequency f=1000Hz bottom electrode P variation relation figure with the alternating electric field amplitude.

The single-phase film sample of Fig. 7 instance 4 300 nanometer ferrous acid bismuths is at different bias magnetic fields, the test frequency f=1000Hz bottom electrode P variation relation figure with the alternating electric field amplitude.

Among the figure: 1-electromagnet, 2-direct supply, 3-gaussmeter, 4-helmholtz coil, 5-function signal generator, 6-bipolar power supply; The 7-oscillograph, 8-lock-in amplifier, 9-computing machine, 10-sample stage, 11-spring probe, 12-probe support; The 13-support spring, 14-gib screw, 15-packing ring, 16-specimen holder, 17-lead-in wire; The 18-testing sample, 19-testing sample substrate electrod, 20-film sample upper surface electrode to be measured, 21-sample stage layer electrodes, 22-specimen holder rotary turnplate.

Embodiment

A kind of multiferroic film material magnetic electricity performance test macro is characterized in that, contains: computing machine, direct current biasing field generator for magnetic, AC magnetic field generating means, tiny signal are gathered multiplying arrangement and film sample probe clamping device, wherein:

The direct current biasing field generator for magnetic contains: electromagnet, direct supply and gaussmeter, wherein:

Gaussmeter, input end links to each other with the measuring control signal output terminal of said computing machine, and the signal output part of this gaussmeter links to each other with the measuring-signal input end of said computing machine;

Direct supply, with said computer interconnection, the control signal of computing machine under receiving, to this computing machine output dc voltage signal, simultaneously, said direct supply is supplied power to said magnet spool;

The AC magnetic field generating means contains: helmholtz coil, function signal generator and bipolar power supply, wherein:

Bipolar power supply is supplied power to said helmholtz coil, and making this helmholtz coil produce frequency is square wave or the sine-wave excitation magnetic field H ac of f;

Helmholtz coil is connected in the said electromagnet in coaxially, in this helmholtz coil, is inserted with the probe of said gaussmeter, in order to measure the size of sinusoidal magnetic field Hac;

Function signal generator, regulation and control are to the waveform and the frequency of the alternating voltage of said bipolar power supply under the control of said computing machine;

The film sample clamping device is inserted horizontally in the said helmholtz coil along the direction that adds sinusoidal magnetic field, and this film sample clamping device is made up of film sample Spin Control part to be measured and film sample retained part to be measured jointly, wherein:

Film sample Spin Control part to be measured comprises: specimen holder and with the coaxial film sample rotary turnplate to be measured that is fixedly connected of this specimen holder, the corner of said film sample rotary turnplate to be measured is finely tuned between+5 °～-5 °;

Film sample retained part to be measured; Contain sample stage, two pieces of spring probe, gib screw, packing ring, support spring, probe support, film sample to be measured, film sample substrate electrod to be measured, film sample upper surface electrode to be measured, film sample to be measured and lead-in wires that structure is identical, wherein:

Sample stage axially is connected with this specimen holder level along said specimen holder;

Film sample to be measured is fixed on the said sample stage;

Two pieces of spring probes that structure is identical, wherein first spring probe links to each other with the substrate electrod of said film sample to be measured in the bottom, and second spring probe links to each other with said film sample upper surface electrode to be measured in the bottom;

Probe support has first, second totally two probe supports, and an end of each probe support links to each other with the top of said spring probe respectively accordingly, and the other end links to each other with a layer electrodes on the said sample stage,

Gib screw; Support spring and pad; Said gib screw insert in the said support spring and pass said packing ring after be connected in the screw of opening on the other end of said probe support, said spring probe and probe support can under said support spring and gib screw effect, horizontally rotate angle adjustment or can be with the different upper-lower positions of adjusting said probe support and spring probe of film sample thickness to be measured;

Said film sample to be measured, first spring probe, first probe support have been combined into first loop jointly; Said film sample to be measured, second spring probe, second probe support have been combined into second loop jointly; These two loops equate on area but current loop in the opposite direction, make positive and negative the cancelling out each other of induced electromotive force that produces separately;

Lead-in wire has first, second totally two lead-in wires, connects respectively between two incoming ends of said two layer electrodes and said sample stage;

Tiny signal is gathered multiplying arrangement; Form by lock-in amplifier and oscillograph serial connection; Two input ends of described lock-in amplifier link to each other with said two pieces of spring probes respectively through lead; The output terminal of this lock-in amplifier inserts oscillographic first passage (1), and the electric current of another output terminal output of described bipolar power supply inserts said oscillographic second channel (2), and this oscillograph and said computing machine are interconnected simultaneously.

The magnetic electricity performance test macro of described multiferroic film material is characterized in that: the helmholtz coil inside of this tester shields through coated with conductive coating material and electromagnet pole shoe altogether.

Below in conjunction with accompanying drawing principle of the present invention, structure and embodiment are further described:

The circuit side connector block diagram of this tester is as shown in Figure 1.The composition of this tester can be divided into following components:

(1) direct current biasing field generator for magnetic

Comprise: electromagnet 1, direct supply 2 and gaussmeter 3.The direct supply drive magnetic produces the direct current biasing magnetic field H _DCThe probe 15 of gaussmeter is placed between the magnetic pole of electromagnet, is used to measure H _DCSize and Orientation.

(2) AC magnetic field generating means

Comprise: helmholtz coil 4, bipolar power supply 6 and function signal generator 5.Function signal generator is exported certain amplitude, and frequency is from sine, square wave or the self-editing waveform voltage of 1Hz-150kHz, and the control bipolar power supply amplifies and adjusts, thereby drives the sinusoidal magnetic field H that helmholtz coil produces same frequency _AcThe sinusoidal magnetic field amplitude that is produced near or surpass some single-phase multiferroic film materials or some ferromagnetic thin film material saturation magnetic fields.

(3) film sample probe clamping device

The film sample clamping device; Be inserted horizontally in the said helmholtz coil along the direction that adds sinusoidal magnetic field; This film sample clamping device is made up of film sample Spin Control part to be measured and film sample retained part to be measured jointly; Wherein: film sample Spin Control part to be measured comprises: specimen holder and with the coaxial film sample rotary turnplate to be measured that is fixedly connected of this specimen holder, the corner of said film sample rotary turnplate to be measured is finely tuned between+5 °～-5 °; Film sample retained part to be measured; Contain sample stage, two pieces of spring probe, gib screw, packing ring, support spring, probe support, film sample to be measured, film sample substrate electrod to be measured, film sample upper surface electrode to be measured, film sample to be measured and lead-in wires that structure is identical, as shown in Figure 2.Testing sample is placed on the sample stage, two pieces of spring probes that structure is identical, and wherein first spring probe links to each other with the substrate electrod of said film sample to be measured in the bottom, and second spring probe links to each other with said film sample upper surface electrode to be measured in the bottom; Probe support has first, second totally two probe supports, and an end of each probe support links to each other with the top of said spring probe respectively accordingly, and the other end links to each other with a layer electrodes on the said sample stage; Gib screw; Support spring and pad; Said gib screw insert in the said support spring and pass said packing ring after be connected in the screw of opening on the other end of said probe support, said spring probe and probe support can under said support spring and gib screw effect, horizontally rotate angle adjustment or can be with the different upper-lower positions of adjusting said probe support and spring probe of film sample thickness to be measured; Spring probe is substrate electrod and the film upper surface electrode of contact membrane sample respectively, probe and support can under the effect of support spring and fixing rivet, horizontally rotate angle adjust with the different height control up and down of thickness of sample, as shown in Figure 3.Said film sample to be measured, first spring probe, first probe support have been combined into first loop jointly; Said film sample to be measured, second spring probe, second probe support have been combined into second loop jointly; These two loops equate on area but current loop in the opposite direction, make positive and negative the cancelling out each other of induced electromotive force that produces separately; Lead-in wire has first, second totally two lead-in wires, connects respectively between two incoming ends of said two layer electrodes and said sample stage.Detect the resistance of sample between two probes through ohmmeter; Through horizontally rotating probe and adjustment height and position; Make sample resistance remain on a steady state value, for common multiferroic film sample, resistance value is generally 100 Ω～20M Ω; When the resistance value registration remains unchanged, then represent to contact between probe and the sample good.

(4) signal pickup assembly

Signal pickup assembly is formed by lock-in amplifier 8 and oscillograph 7 serial connections; Two input ends of described lock-in amplifier link to each other with said two pieces of spring probes respectively through lead; The output terminal of this lock-in amplifier inserts oscillographic first passage (1); And the electric current of another output terminal output of described bipolar power supply inserts said oscillographic second channel (2), and this oscillograph and said computing machine are interconnected simultaneously, and be as shown in Figure 1.

(5) computing machine

Computing machine 9 links to each other with direct supply 2, gaussmeter 3, function signal generator 5 and oscillograph 7 respectively through communication interface, and computing machine has been installed the communications control software of each instrument respectively.

The concrete course of work is:

1) film sample to be measured is placed film sample probe clamping device to be measured, wherein one piece of spring probe links to each other with film sample substrate electrod to be measured, and another piece spring probe links to each other with film sample upper surface electrode to be measured; Utilize ohmmeter check probe and sample contact quality, and the adjustment probe location, it is good to make it contact.

2) film sample to be measured and film sample clamping device to be measured are together placed magnetic field;

3) type of analysis and judgement film sample is selected the method for testing that adapts;

Method one:

4) computing machine utilizes function signal generator regulation and control waveform to remove to control bipolar power supply, and making bipolar power supply drive helmholtz coil generation frequency is the square wave excitation magnetic field H of f _Ac, the probe of gaussmeter is placed on the helmholtz coil inside between electromagnet pole, measure sinusoidal magnetic field H _AcSize;

5) computing machine obtains film sample response voltage to be measured through lock-in amplifier, and the signal of lock-in amplifier outputs to oscillographic first passage (1) simultaneously;

6) pass through to analyze the response wave shape that sample produces in the oscillograph, manual fine-tuning film sample whirligig to be measured, making the sample response waveform is square-wave waveform, and fixing this position, this moment is owing to the spike waveform that electromagnetic induction phenomenon produces disappears;

7) computing machine utilizes the direct supply drive magnetic to produce direct current biasing magnetic field, through changing the size of direct supply output current, changes the direct current biasing magnetic field H _DCSize, measure the direct current biasing magnetic field H through gaussmeter _DCSize and Orientation;

8) computing machine reads sample response voltage value U (H through lock-in amplifier _DC), according to following formula, carry out data processing and obtain this direct current biasing magnetic field H _DCFollowing magnetoelectricity voltage coefficient α _EAmplitude, wherein t is the thickness of film sample to be measured;

${\mathrm{\α}}_E=\frac{U\left(H_{\mathrm{DC}}\right)}{t\·H_{\mathrm{ac}}}$

9) repeating step 7) to 87), draw magnetoelectricity voltage coefficient α under a certain fixed frequency f _EWith the direct current biasing magnetic field H _DCChanging Pattern.

Method two:

4) computing machine utilizes function signal generator regulation and control waveform to remove to control bipolar power supply, makes bipolar power supply drive helmholtz coil and produces the sinusoidal excitation magnetic field H _Ac, and the output current sample waveform of bipolar power supply outputed to oscillographic second channel (2), the helmholtz coil that the probe of gaussmeter is placed between electromagnet pole is inner, measure sinusoidal magnetic field H _AcSize;

5) computing machine obtains sample response voltage through lock-in amplifier, and the signal of lock-in amplifier outputs to oscillographic first passage (1) simultaneously;

6) through the phase place ψ between the current sample waveform of analyzing film sample to be measured produces in the oscillograph response wave shape and bipolar power supply generation; Manual fine-tuning film sample whirligig to be measured; Making between sample response waveform and the current sample waveform phase differential is 0 or pi/2, and fixing this position;

7) computing machine utilizes the direct supply drive magnetic to produce direct current biasing magnetic field, through changing the size of direct supply output current, changes the direct current biasing magnetic field H _DCSize, measure the direct current biasing magnetic field H through gaussmeter _DCSize and Orientation;

8) computing machine changes the frequency of sinusoidal sinusoidal magnetic field through the output frequency that changes function signal generator, and the constant current of control bipolar power supply output keeps constant sinusoidal magnetic field amplitude H _AcSize;

9) computing machine reads sample response voltage value U (f) through lock-in amplifier, and according to following formula, computing machine carries out data processing and obtains magnetoelectricity voltage coefficient α under a certain frequency f _EAmplitude, wherein t is the thickness of film sample to be measured;

${\mathrm{\α}}_E=\frac{U\left(f\right)}{t\·H_{\mathrm{ac}}}$

10) repeating step 8) to 9), draw at a certain fixedly D.C. magnetic field H _DCFollowing magnetoelectricity voltage coefficient α _EChanging Pattern with alternative frequency f.

Method three:

4) computing machine utilizes function signal generator regulation and control waveform to remove to control bipolar power supply, makes bipolar power supply drive helmholtz coil and produces the sinusoidal excitation magnetic field H _Ac, and the current sample waveform of bipolar power supply output outputed to oscillograph second channel (2), the helmholtz coil that the probe of gaussmeter is placed between electromagnet pole is inner, measure sinusoidal magnetic field H _AcSize;

5) computing machine obtains sample response voltage through lock-in amplifier, and the signal of lock-in amplifier outputs to oscillographic first passage (1) simultaneously;

6) through the phase place ψ between the current sample waveform of analyzing film sample to be measured produces in the oscillograph response wave shape and bipolar power supply generation; Manual fine-tuning film sample whirligig to be measured; Making between sample response waveform and the current sample waveform phase differential is 0 or pi/2, and fixing this position;

7) computing machine changes the amplitude H of sinusoidal sinusoidal magnetic field through the output amplitude that changes function signal generator _AcSize;

8) computing machine reads sample response voltage value U (H through lock-in amplifier _Ac), according to following formula, carry out data processing and obtain a certain fixed frequency f, this sinusoidal magnetic field H _AcBottom electrode P value, wherein t is the thickness of film sample to be measured, ε ₀Be permittivity of vacuum, ε _rRelative dielectric constant for film sample to be measured;

$P={\mathrm{\ϵ}}_0({\mathrm{\ϵ}}_r-1)\frac{U\left(H_{\mathrm{ac}}\right)}{t_{\mathrm{ac}}}$

9) repeating step 7) to 8), draw under a certain fixed frequency f multiferroic film sample electrode value P with sinusoidal magnetic field H _AcChanging Pattern.

Method four:

4) computing machine utilizes function signal generator regulation and control waveform to remove to control bipolar power supply, makes bipolar power supply drive helmholtz coil and produces the sinusoidal excitation magnetic field H _Ac, and the current sample waveform of bipolar power supply output outputed to oscillograph second channel (2), the helmholtz coil that the probe of gaussmeter is placed between electromagnet pole is inner, measure sinusoidal magnetic field H _AcSize;

5) computing machine obtains sample response voltage through lock-in amplifier, and the signal of lock-in amplifier outputs to oscillographic first passage (1) simultaneously;

6) through the phase place ψ between the current sample waveform of analyzing film sample to be measured produces in the oscillograph response wave shape and bipolar power supply generation; Manual fine-tuning film sample whirligig to be measured; Making between sample response waveform and the current sample waveform phase differential is 0 or pi/2, and fixing this position;

7) computing machine utilizes the direct supply drive magnetic to produce direct current biasing magnetic field, through changing the size of direct supply output current, changes the direct current biasing magnetic field H _DCSize, measure the direct current biasing magnetic field H through gaussmeter _DCSize and Orientation;

8) computing machine changes the amplitude H of sinusoidal sinusoidal magnetic field through the output amplitude that changes function signal generator _AcSize;

9) computing machine reads sample response voltage value U (H through lock-in amplifier _DC, H _Ac), according to following formula, carry out data processing and obtain at this bias magnetic field H _DC, a certain fixed frequency f, this sinusoidal magnetic field H _AcUnder electric polarization P value, wherein t is the thickness of film sample to be measured, ε ₀Be permittivity of vacuum, ε _rRelative dielectric constant for film sample to be measured;

$P={\mathrm{\ϵ}}_0({\mathrm{\ϵ}}_r-1)\frac{U(H_{\mathrm{DC}},H_{\mathrm{ac}})}{t_{\mathrm{ac}}}$

10) repeating step 7) to 9), draw at different bias magnetic field H _DCDown, a certain fixed frequency f bottom electrode P value is with alternating electric field H _AcThe rule that changes

Below, be instance with dissimilar multiferroic film samples respectively, the operating process of different method of testings according to the invention is described.

A) instance one: lead zirconate titanate (PZT)-many iron of cobalt ferrite (CFO) lamination property laminated film

Use sol-gel method on the platinum plating silicon chip, to prepare lead zirconate titanate (PZT)-many iron of cobalt ferrite (CFO) lamination property laminated film; And plating platinum film upper surface electrode; Testing sample is utilized Probe clip to be held in sample stage and is fixed on the specimen holder, guarantee that contact is good, set H _DC, f, make sinusoidal magnetic field produce square-wave waveform, rotate rotating disk then and in ± 5 ° of scopes, rotate specimen holder gently; Treat that the spike in the response signal waveform partly eliminates; Fixing this angle changes the direct current biasing magnetic field value successively, from lock-in amplifier, reads the magnetoelectricity signal magnitude under each bias magnetic field through computing machine successively; Obtain the amplitude of magnetic-electric coefficient and the Changing Pattern between the direct current biasing magnetic field according to computing formula, the result is as shown in Figure 4.

B) instance two: barium titanate (BTO)-many iron of nickel ferrite based magnetic loaded (NFO) lamination property laminated film

Use pulse laser sediment method to prepare barium titanate (BTO)-many iron of nickel ferrite based magnetic loaded (NFO) lamination property laminated film on the strontium titanate monocrystal chip of niobium mixing; And plating platinum film upper surface electrode; Testing sample is utilized Probe clip to be held in sample stage and is fixed on the specimen holder, guarantee that contact is good, set H _DC, H _DC, make sinusoidal magnetic field produce sinusoidal waveform, rotate rotating disk then and in ± 5 ° of scopes, rotate specimen holder gently; Treat that response signal waveform and reference signal phase differential are 0 or during π; Fixing this angle changes the driving magnetic field frequency successively, from lock-in amplifier, reads the magnetoelectricity signal magnitude under each bias magnetic field through computing machine successively; Obtain the amplitude of magnetic-electric coefficient and the Changing Pattern between the sinusoidal magnetic field frequency according to computing formula, the result is as shown in Figure 5.

C) instance three: the single-phase multiferroic film of ferrous acid bismuth (BFO)

Use colloidal sol on the platinum plating silicon chip, prepare the single-phase multiferroic film of ferrous acid bismuth than method, and the plating platinum film upper surface electrode with withing fixed attention, testing sample is utilized Probe clip to be held in sample stage and is fixed on the specimen holder, guarantee contact well, setting f, H _DC=0Oe; Make sinusoidal magnetic field produce sinusoidal waveform; Rotate rotating disk then and in ± 5 ° of scopes, rotate specimen holder gently, treat that response signal waveform and reference signal phase differential are 0 or during π, fixing this angle; Change the amplitude of driving magnetic field successively; From lock-in amplifier, read the magnetoelectricity signal magnitude under each different big or small sinusoidal magnetic field through computing machine successively, obtain the Changing Pattern of this film sample between no bias magnetic field bottom electrodeization and sinusoidal magnetic field frequency according to computing formula, the result is as shown in Figure 6.

D) instance four: the single-phase multiferroic film of ferrous acid bismuth (BFO)

Use colloidal sol on the platinum plating silicon chip, to prepare the single-phase multiferroic film of ferrous acid bismuth than method with fixed attention; And ferro-nickel alloy film upper surface electrode, testing sample is utilized Probe clip to be held in sample stage and is fixed on the specimen holder, guarantee that contact is good; Set f=1000Oe; Make sinusoidal magnetic field produce sinusoidal waveform, rotate rotating disk then and in ± 5 ° of scopes, rotate specimen holder gently, treat that response signal waveform and reference signal phase differential are 0 or during π; Fixing this angle; Change the direct current biasing magnetic field value to be respectively-25.44Oe, 0Oe and 25.43Oe, and under each direct current biasing magnetic field condition, change the amplitude of driving magnetic field successively, from lock-in amplifier, read the magnetoelectricity signal magnitude under each different big or small sinusoidal magnetic field through computing machine successively; Obtain the Changing Pattern of this film sample between different bias magnetic field bottom electrodeizations and sinusoidal magnetic field frequency according to computing formula, the result is as shown in Figure 7.

This tester provides and has comprised D.C. magnetic field H _DC, AC magnetic field H _Ac, three kinds of frequency f test changing factor respectively to four kinds of magnetic electricity performance measuring methods of dissimilar multiferroic film materials.

1) the magnetoelectricity voltage coefficient is with the variation relation of frequency f

2) the magnetoelectricity voltage coefficient is with bias magnetic field H _DCVariation relation;

3) the mangneto electric polarization is with AC magnetic field H _AcVariation relation;

4) the mangneto electric polarization is in the different DC biased magnetic field H _DCDown, with AC magnetic field H _AcVariation relation.

Claims (6)

1. A multiferroic thin film material magnetoelectric performance testing system, is characterized in that, contains: computer, DC bias magnetic field generating device, AC magnetic field generating device, tiny signal acquisition amplification device and thin film sample probe clamping device, wherein : The DC bias magnetic field generating device contains: an electromagnet, a DC power supply and a gauss meter for supplying power to the electromagnet, wherein: Gauss meter, the input end is connected with the measurement control signal output end of the computer, and the signal output end of the Gauss meter is connected with the measurement signal input end of the computer; A DC power supply is interconnected with the computer, receives a control signal from the computer, and outputs a DC voltage signal to the computer, and at the same time, the DC power supply supplies power to the coil of the electromagnet; The AC magnetic field generating device includes: Helmertz coil, function signal generator and bipolar power supply, among which: A bipolar power supply supplies power to the Helmertz coil, so that the Helmertz coil generates a square wave or sine wave excitation magnetic field H _ac with a frequency f; A Helmertz coil coaxially connected in the electromagnet, a probe of the Gaussmeter is inserted in the Helmertz coil for measuring the magnitude of the sinusoidal magnetic field _Hac ; a function signal generator to regulate the waveform and frequency of the alternating voltage to the bipolar power supply under the control of the computer; The thin film sample holding device is horizontally inserted into the Helmertz coil along the direction of the applied sinusoidal magnetic field, and the thin film sample holding device is composed of the rotation control part of the film sample to be tested and the holding part of the film sample to be tested. in: The rotation control part of the film sample to be tested includes: a sample rod and a rotating turntable for the film sample to be measured coaxially and fixedly connected with the sample rod, and the rotation angle of the rotating turntable for the film sample to be measured is fine-tuned between +5°～-5° ; The clamping part of the film sample to be tested includes a sample stage, two spring probes with the same structure, fixing screws, washers, support springs, probe holders, the film sample to be tested, the substrate electrode of the film sample to be tested, and the film sample to be tested The upper surface electrode, the thin film sample to be tested and the lead wires, wherein: a sample stage connected horizontally to the sample rod along the axial direction of the sample rod; The film sample to be tested is fixed on the sample stage; Two spring probes with the same structure, wherein the first spring probe is connected to the substrate electrode of the film sample to be tested at the bottom, and the second spring probe is connected to the electrode on the upper surface of the film sample to be tested at the bottom connected; The probe holder has two probe holders, first and second, one end of each probe holder is correspondingly connected to the top of the spring probe, and the other end is connected to an electrode coating on the sample stage. connected, Fixing screws, supporting springs and gaskets, the fixing screws are inserted into the supporting springs and connected to the screw holes on the other end of the probe holder after passing through the washer, the spring probes and probes The needle support can adjust the horizontal rotation angle under the action of the support spring and the fixing screw or can adjust the upper and lower positions of the probe support and the spring probe according to the thickness of the film sample to be measured; The film sample to be tested, the first spring probe, and the first probe bracket jointly form a first loop, and the film sample to be tested, the second spring probe, and the second probe bracket jointly form a second loop. Loop, the two loops are equal in area but the direction of the current loop is opposite, so that the positive and negative induced electromotive forces generated by each cancel each other out; Lead wires, including the first and the second two lead wires, respectively connected between the two electrode coatings and the two access ends of the sample stage; The small signal acquisition and amplification device is formed by a lock-in amplifier and an oscilloscope connected in series. The two input terminals of the lock-in amplifier are respectively connected to the two spring probes through wires, and the output terminals of the lock-in amplifier are connected to the The first channel (1) of the oscilloscope, and the current output from the other output end of the bipolar power supply is connected to the second channel (2) of the oscilloscope, and at the same time, the oscilloscope is interconnected with the computer. 2. The magnetoelectric performance testing system of multiferroic thin film material according to claim 1, characterized in that: the inside of the Helmertz coil of the tester is shielded with the electromagnet pole piece by coating a conductive coating material. 3. the test method of a kind of magnetoelectric property proposed by a kind of multiferroic thin film material magnetoelectric property test system according to claim 1, is characterized in that, contains following steps successively: 1) Place the film sample to be tested in the probe holding device of the film sample to be tested, one of the spring probes is connected to the substrate electrode of the film sample to be tested, and the other spring probe is connected to the electrode on the upper surface of the film sample to be tested connected; 2) placing the film sample to be tested together with the film sample holding device to be tested in a magnetic field; 3) The computer uses the function signal generator to adjust the waveform to control the bipolar power supply, so that the bipolar power supply drives the Helmertz coil to generate a square wave excitation magnetic field H _ac with a frequency of f, and the probe of the Gauss meter is placed at the magnetic pole of the electromagnet Inside the Helmertz coil between, measure the magnitude of the sinusoidal magnetic field H _ac ; 4) The computer obtains the response voltage of the film sample to be tested through the lock-in amplifier, and the signal of the lock-in amplifier is simultaneously output to the first channel of the oscilloscope; 5) By analyzing the response waveform generated by the sample in the oscilloscope, manually fine-tune the rotating device of the film sample to be tested, so that the sample response waveform is a square wave waveform, and fix the position. At this time, the peak waveform due to the electromagnetic induction phenomenon disappears; 6) The computer utilizes the DC power supply to drive the electromagnet to generate a DC bias magnetic field, changes the size of the DC bias magnetic field H _DC by changing the output current of the DC power supply, and measures the size and direction of the DC bias magnetic field H _DC through a Gauss meter; 7) The computer reads the sample response voltage value U(H _DC ) through the lock-in amplifier, and performs data processing according to the following formula to obtain the magnitude of the magnetoelectric voltage coefficient α _E under the DC bias magnetic field H _DC , where t is the value to be measured The thickness of the film sample; ${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; DC</span>}}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ac</span>}}}$ 8) Repeat steps 6) to 7) to obtain the variation law of the magnetoelectric voltage coefficient α _E with the DC bias magnetic field H _DC at a certain fixed frequency f. 4. the test method of a kind of magnetoelectric property proposed by a kind of multiferroic thin film material magnetoelectric property test system according to claim 1, is characterized in that, contains following steps successively: 1) Place the film sample to be tested in the probe holding device of the film sample to be tested, one of the spring probes is connected to the substrate electrode of the film sample to be tested, and the other spring probe is connected to the electrode on the upper surface of the film sample to be tested connected; 2) placing the film sample to be tested together with the film sample holding device to be tested in a magnetic field; 3) The computer uses the function signal generator to adjust the waveform to control the bipolar power supply, so that the bipolar power supply drives the Helmertz coil to generate a sinusoidal excitation magnetic field H _ac , and outputs the output current sampling waveform of the bipolar power supply to the oscilloscope's first Two channels, place the probe of the gauss meter inside the Helmertz coil located between the magnetic poles of the electromagnet, and measure the size of the sinusoidal magnetic field H _ac ; 4) The computer obtains the sample response voltage through the lock-in amplifier, and the signal of the lock-in amplifier is simultaneously output to the first channel of the oscilloscope; 5) By analyzing the phase Ψ between the response waveform generated by the film sample to be tested in the oscilloscope and the current sampling waveform generated by the bipolar power supply, manually fine-tune the rotating device of the film sample to be tested so that the phase between the sample response waveform and the current sampling waveform The difference is 0 or π/2, and the position is fixed; 6) The computer utilizes the DC power supply to drive the electromagnet to generate a DC bias magnetic field, changes the size of the DC bias magnetic field H _DC by changing the output current of the DC power supply, and measures the size and direction of the DC bias magnetic field H _DC through a Gauss meter; 7) The computer changes the frequency of the sinusoidal sinusoidal magnetic field by changing the output frequency of the function signal generator, and controls the constant current output by the bipolar power supply to maintain a constant sinusoidal magnetic field amplitude H _ac ; 8) The computer reads the sample response voltage value U(f) through the lock-in amplifier. According to the following formula, the computer performs data processing to obtain the amplitude of the magnetoelectric voltage coefficient α _E at a certain frequency f, where t is the value of the film sample to be tested thickness; ${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; E.</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ac</span>}}}$ 9) Repeat steps 7) to 8) to obtain the change law of the magnetoelectric voltage coefficient α _E with the alternating frequency f under a certain fixed DC magnetic field H _DC . 5. the test method of a kind of magnetoelectric property proposed by a kind of multiferroic thin film material magnetoelectric property test system according to claim 1, is characterized in that, contains following steps successively: 1) Place the film sample to be tested in the probe holding device of the film sample to be tested, one of the spring probes is connected to the substrate electrode of the film sample to be tested, and the other spring probe is connected to the electrode on the upper surface of the film sample to be tested connected; 2) placing the film sample to be tested together with the film sample holding device to be tested in a magnetic field; 3) The computer uses the function signal generator to adjust the waveform to control the bipolar power supply, so that the bipolar power supply drives the Helmertz coil to generate a sinusoidal excitation magnetic field Hac, and outputs the current sampling waveform output by the bipolar power supply to the second channel of the oscilloscope (2), the probe of the gauss meter is placed inside the Helmertz coil between the magnetic poles of the electromagnet, and the size of the sinusoidal magnetic field Hac is measured; 4) The computer obtains the sample response voltage through the lock-in amplifier, and the signal of the lock-in amplifier is simultaneously output to the first channel of the oscilloscope; 5) By analyzing the phase Ψ between the response waveform generated by the film sample to be tested in the oscilloscope and the current sampling waveform generated by the bipolar power supply, manually fine-tune the rotating device of the film sample to be tested so that the phase between the sample response waveform and the current sampling waveform The difference is 0 or π/2 radians, and the position is fixed; 6) The computer changes the magnitude of the amplitude Hac of the sinusoidal magnetic field by changing the output amplitude of the function signal generator; 7) The computer reads the sample response voltage value U(Hac) through the lock-in amplifier, and performs data processing according to the following formula to obtain a certain fixed frequency f and the lower electrode polarization P value of the sinusoidal magnetic field Hac, where t is the value of the film sample to be tested thickness, _ε0 is the vacuum dielectric constant, and εr is the relative dielectric constant of the film sample to be measured; $\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ac</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; ac</span>}}}$ 8) Repeat steps 6) to 7) to obtain the change law of the electric polarization value P of the multiferroic thin film sample with the sinusoidal magnetic field H _ac at a certain fixed frequency f. 6. the test method of a kind of magnetoelectric property proposed by a kind of multiferroic thin film material magnetoelectric property test system according to claim 1, is characterized in that, contains following steps successively: 1) Place the film sample to be tested in the probe holding device of the film sample to be tested, one of the spring probes is connected to the substrate electrode of the film sample to be tested, and the other spring probe is connected to the electrode on the upper surface of the film sample to be tested connected; 2) placing the film sample to be tested together with the film sample holding device to be tested in a magnetic field; 3) The computer uses the function signal generator to adjust the waveform to control the bipolar power supply, so that the bipolar power supply drives the Helmertz coil to generate a sinusoidal excitation magnetic field H _ac , and outputs the current sampling waveform output by the bipolar power supply to the second oscilloscope. Channel, place the probe of the gauss meter inside the Helmertz coil located between the poles of the electromagnet, and measure the magnitude of the sinusoidal magnetic field H _ac ; 4) The computer obtains the sample response voltage through the lock-in amplifier, and the signal of the lock-in amplifier is simultaneously output to the first channel of the oscilloscope; 5) By analyzing the phase Ψ between the response waveform generated by the film sample to be tested in the oscilloscope and the current sampling waveform generated by the bipolar power supply, manually fine-tune the rotating device of the film sample to be tested so that the phase between the sample response waveform and the current sampling waveform The difference is 0 or π/2, and the position is fixed; 6) The computer utilizes the DC power supply to drive the electromagnet to generate a DC bias magnetic field, changes the size of the DC bias magnetic field H _DC by changing the output current of the DC power supply, and measures the size and direction of the DC bias magnetic field H _DC through a Gauss meter; 7) The computer changes the amplitude H _ac of the sinusoidal magnetic field by changing the output amplitude of the function signal generator; 8) The computer reads the sample response voltage value U(H _DC , H _ac ) through the lock-in amplifier, and performs data processing according to the following formula to obtain the bias magnetic field H _DC , a certain fixed frequency f, and the sinusoidal magnetic field H _ac . The electric polarization P value of , wherein t is the thickness of the thin film sample to be measured, ε ₀ is the vacuum dielectric constant, and ε _r is the relative dielectric constant of the thin film sample to be measured; $\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; DC</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; ac</span>}}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; ac</span>}}}$ 9) Repeat steps 6) to 8) to obtain the rule that the electric polarization P value changes with the alternating electric field H _ac at a certain fixed frequency f under different bias magnetic fields H _DC .

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