CN103904211B - A kind of magnetic field detectors based on vertical exchange coupling and preparation and application thereof - Google Patents

Abstract

The invention relates to a magnetic field detector based on vertical exchange coupling and its preparation and use method. The preparation method of the magnetic field detector includes the following steps: using magnetron sputtering or electron beam evaporation method, sequentially depositing a bottom electrode, a The ferromagnetic layer, the non-magnetic layer and the top electrode are used to obtain a multilayer film structure; the obtained multilayer film structure is processed into a cross-shaped structure by using ultraviolet exposure and argon ion etching processes. The magnetic field detector prepared by the present invention comprises a substrate, a bottom electrode, a ferromagnetic layer, a nonmagnetic layer and a top electrode, the substrate adopts a cross-shaped structure, and the bottom electrode, the ferromagnetic layer, the nonmagnetic layer and the top electrode are sequentially deposited on the substrate. On-chip, and the shape is matched with the shape of the substrate; the ferromagnetic layer is composed of a perpendicular magnetization film, the non-magnetic layer is composed of an antiferromagnetic layer or an oxide layer, and both the bottom electrode and the top electrode are Pt electrodes. The invention can be widely used in the magnetic field detection process.

Description

A magnetic field detector based on vertical exchange coupling and its preparation and use method

technical field

The invention relates to a magnetic field detector and its preparation and use method, in particular to a magnetic field detector based on vertical exchange coupling and its preparation and use method.

Background technique

The magnetic transmission test includes using the principles of AHE (Anomalous Hall effect, abnormal Hall effect), PHE (PlanarHall effect, planar Hall effect) and anisotropic magnetoresistance effect to detect the magnetization characteristics of the magnetic system. The magnetic sensor of the corresponding principle can accurately Detecting the size and direction of the magnetic field is used in many aspects such as magnetic memory, biosensor, aerospace navigation system and automatic control system. PHE sensors are usually made of in-plane magnetized materials, which are easy to obtain a linear response. However, the reduction in the size of PHE sensors will make the magnetization state of the sensitive layer affected by thermal effects and external magnetic fields, resulting in increased noise and signal instability. and attenuation of the output signal. On the contrary, for the magnetic system with good thermal stability and easy magnetization perpendicularly, the AHE sensor is the focus of people's attention. When the AHE sensor is used to detect the signal, it is mostly concentrated in the direction perpendicular to the film surface, while ignoring other factors in the three-dimensional space. direction.

Contents of the invention

In view of the above problems, the object of the present invention is to provide a magnetic field detector based on vertical exchange coupling and its preparation and use method. The preparation method of the present invention utilizes the magnetic thin film system of vertical exchange coupling, combined with AHE and PHE, to prepare a A magnetic field detector with small size, high resolution and simple structure, the magnetic field detector of the present invention can detect the magnitude and direction of the magnetic field in three-dimensional space.

To achieve the above object, the present invention adopts the following technical solutions: a magnetic field detector based on vertical exchange coupling, characterized in that: it includes a substrate, a bottom electrode, a ferromagnetic layer, a nonmagnetic layer and a top electrode, and the substrate Using a cross-shaped structure, the bottom electrode, ferromagnetic layer, non-magnetic layer and top electrode are sequentially deposited on the substrate, and the shapes of the bottom electrode, ferromagnetic layer, non-magnetic layer and top electrode are the same as those of the The shapes of the substrates are arranged in a matching manner; the ferromagnetic layer is composed of a perpendicular magnetization film, the nonmagnetic layer is composed of an antiferromagnetic layer or an oxide layer, and both the bottom electrode and the top electrode are Pt electrodes.

The thickness of the non-magnetic layer constituting the oxide layer is 0.5 nm to 1.5 nm.

The substrate adopts one of Si(100)/SiO ₂ common substrate, MgO single crystal substrate, SrTiO ₃ single crystal substrate and ferroelectric substrate, and the ferroelectric substrate adopts BaTiO ₃ , PZT and One of PMN-PT.

The perpendicular magnetization film constituting the ferromagnetic layer is one of vertical magnetization [Co/Pt] _n multilayer film, [Co/Pd] _n multilayer film, [Co/Ni] _n multilayer film and CoFeB, n=1～10; when the vertical magnetization film adopts [Co/Pt] _n multilayer film, the Co layer and the Pt layer are periodically deposited repeatedly, the thickness of each Co layer is 0.3nm～0.8nm, and the thickness of each Pt layer is 0.8nm～1.5nm; when the vertical magnetization film adopts [Co/Pd] _n multilayer film, the Co layer and Pd layer are periodically deposited repeatedly, the thickness of each Co layer is 0.3nm～0.8nm, and the thickness of each Pd layer is 0.8nm～1.5nm; when the [Co/Ni] _n multilayer film is used for the vertical magnetization film, the Co layer and the Ni layer are periodically deposited repeatedly, the thickness of each Co layer is 0.3nm～0.8nm, and the thickness of each Ni layer is 0.8nm-1.5nm; when CoFeB is used for the perpendicular magnetization film, the thickness of CoFeB is 0.7nm-1.5nm.

The antiferromagnetic layer constituting the nonmagnetic layer adopts one of Mn alloy and oxide antiferromagnetic material; the Mn alloy adopts one of IrMn, FeMn and PtMn, and the oxide antiferromagnetic material adopts NiO, One of Cr ₂ O ₃ and Sr ₂ IrO ₄ .

A method for preparing a magnetic field detector based on vertical exchange coupling, which includes the following steps: 1) using magnetron sputtering or electron beam evaporation to sequentially deposit a bottom electrode, a ferromagnetic layer, and a nonmagnetic layer on a substrate and the top electrode to obtain a multilayer film structure; 2) Using ultraviolet exposure and argon ion etching process, the obtained multilayer film structure is processed into a cross-shaped structure, and the area of the rectangle where the cross-shaped structure is located is 500×300μm ² ~1000× 600 μm ² , and the cross-overlapping portion at the center of the cross-shaped structure has an area of 5×3 μm ² to 40×30 μm ² .

A method for using the magnetic field detector based on vertical exchange coupling, which includes the following steps: 1) placing the magnetic field detector in a magnetic field whose direction and magnitude are unknown; 2) placing the magnetic field detector between the first end point and the second end point The current I is passed through, and the Hall resistance is measured between the third terminal and the fourth terminal; the magnetic field detector is rotated, and the resistance values of any six different magnetic field sizes are respectively read at a certain angle. Among them, the Hall resistance values R ₁ , R ₂ and R ₃ under three positive magnetic fields; the Hall resistance values R ₄ , R ₅ and R ₆ under three negative magnetic fields, and according to the relationship between the Hall resistance values 3) For the magnetic field whose direction is determined in step 2), the following steps are used to determine the size: ① Take the surface of the magnetic field detector as the xy plane, where the plane parallel to the passage between the first end point and the second end point The direction of the current I is the x-axis, the direction perpendicular to the current I is the y-axis, and the direction perpendicular to the xy plane is used as the z-axis to establish a space coordinate system; ② Place the magnetic field detector in the magnetic field whose direction is determined in step 2) , make the x-axis parallel to the direction of the magnetic field, rotate the magnetic field detector 360° around the z-axis, measure and record the Hall resistance value during the rotation of the magnetic field detector around the z-axis; according to the angle and Measure the obtained Hall resistance value, and draw a resistance-angle curve; ③ Place the magnetic field detector in several magnetic fields with known directions and sizes, and use the same method as step ① and step ②, according to the magnetic field detector around the z-axis Draw a number of standard resistance-angle curves based on the angle of rotation and the measured Hall resistance value; ④Compare the drawn resistance-angle curve with several standard resistance-angle curves to find out the resistance-angle curve that is consistent with the drawn resistance-angle curve. The standard resistance-angle curve with the same curve, the magnetic field corresponding to this standard resistance-angle curve is the size of the magnetic field to be determined.

In the step 3), the magnetic field whose direction and size are known ranges from 0.01kOe to 90kOe.

A method for using the magnetic field detector based on vertical exchange coupling, which includes the following steps: 1) placing the magnetic field detector in a magnetic field whose direction and magnitude are unknown; 2) placing the magnetic field detector between the first end point and the second end point Pass a current I between the third terminal and the fourth terminal to measure the Hall resistance; rotate the magnetic field detector to read the Hall resistance values under any six different magnetic field sizes at a certain angle, among which three Hall resistance values R ₁ , R ₂ and R ₃ under a positive magnetic field; Hall resistance values R ₄ , R ₅ and R ₆ under three negative magnetic fields, and determine the direction of the magnetic field according to the relationship between each Hall resistance value ;3) For the magnetic field whose direction is determined in step 2), the process of determining the magnitude of its magnetic field is: place the magnetic field detector with the ferroelectric substrate in a magnetic field of unknown magnitude, and let the direction of the magnetic field be perpendicular to the film of the magnetic field detector On the surface, apply a voltage ranging from -10V to 10V on the ferroelectric substrate, and record the voltage value when the Hall resistance between the third terminal and the fourth terminal changes. The voltage value at this time corresponds to the correction of the vertical exchange coupling system. The coercive force is the magnitude of the magnetic field.

The present invention has the following advantages due to the adoption of the above technical scheme: 1. The present invention deposits a bottom electrode, a ferromagnetic layer, a nonmagnetic layer and a top electrode successively on the substrate due to the use of magnetron sputtering or electron beam evaporation methods to obtain multilayer film structure, and adopts ultraviolet exposure and argon ion etching process, the multilayer film structure obtained is processed into a cross-shaped magnetic field detector, so the preparation method of the magnetic field detector of the present invention is simple, and cost is low, and the many prepared The interface of the layer film structure is clear, flat and has good adhesion, and has good vertical easy magnetization characteristics. 2. Since the size of the magnetic field detector of the present invention is on the order of microns, the present invention can be used to detect the direction and magnitude of the magnetic field in a narrow space or at a precise location. 3. Since the magnetic field detector of the present invention adopts a vertical magnetization film with good thermal stability for the ferromagnetic layer, the present invention can reduce the interference of thermal effects on the signal, making the test results more accurate, and the resolution of the present invention is high, and the detected magnetic field The orientation can be accurate to within 0.2°. 4. Since the magnetic field detector of the present invention is used to detect the magnetic field, the coercive force of the perpendicular magnetization system can be regulated through the ferroelectric substrate, so the present invention can accurately judge the change of the Hall resistance under different voltages applied to the ferroelectric substrate The size of the magnetic field. 5. Since the Hall signal of the magnetic field detector is very sensitive to the direction of the magnetic field when the magnetic field detector of the present invention is used to detect the magnetic field, the magnetic field detector of the present invention can combine the abnormal Hall resistance and the planar Hall resistance to realize the detection of the magnetic field. Detection of the direction and magnitude of the magnetic field in three-dimensional space. 6. The magnetic field detector of the present invention is suitable for determining the direction of the magnetic field in an environment with a temperature range of 2K to 400K. In different temperature environments, when the magnetic field detector of the present invention is applied to a small magnetic measuring device with a closed sample cavity, it can It can accurately determine the magnitude and direction of the magnetic field at different positions in the sample cavity and is very convenient to use. Based on the above advantages, the present invention can be widely applied in the process of magnetic field detection.

Description of drawings

Fig. 1 is the partial structure schematic diagram of magnetic field detector of the present invention

Fig. 2 is a schematic diagram of the use state of the magnetic field detector of the present invention

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, the magnetic field detector based on vertical exchange coupling of the present invention comprises substrate 1, bottom electrode 2, ferromagnetic layer 3, nonmagnetic layer 4 and top electrode 5, and substrate 1 adopts cross-shaped structure, and bottom electrode 2 , ferromagnetic layer 3, nonmagnetic layer 4 and top electrode 5 are sequentially deposited on substrate 1, and the shapes of bottom electrode 2, ferromagnetic layer 3, nonmagnetic layer 4 and top electrode 5 are all in the same shape as substrate 1. Match settings. Among them, the ferromagnetic layer 3 is composed of a perpendicular magnetization film, the nonmagnetic layer 4 is composed of an antiferromagnetic layer or an oxide layer with a thickness of 0.5nm-1.5nm, and both the bottom electrode 2 and the top electrode 5 are Pt electrodes.

In the above embodiment, the substrate 1 adopts Si(100)/SiO ₂ common substrate, MgO single crystal substrate, SrTiO ₃ (strontium titanate) single crystal substrate and BaTiO ₃ , PZT (lead zirconate titanate), PMN -PT (lead magnesium niobate-lead titanate) and other ferroelectric substrates.

In the above-mentioned embodiments, the perpendicular magnetization film adopts vertical magnetization [Co/Pt] _n multilayer film, [Co/Pd] _n multilayer film, [Co/Ni] _n multilayer film and the thickness is 0.7nm～1.5nm One of CoFeB. Among them, n=1～10.

When the [Co/Pt] _n multilayer film is used for the vertical magnetization film, the Co layer and the Pt layer are deposited periodically, and the thickness of each Co layer is 0.3nm-0.8nm, and the thickness of each Pt layer is 0.8nm-1.5nm.

When the vertical magnetization film adopts [Co/Pd] _n multilayer film, the Co layer and the Pd layer are periodically deposited repeatedly, the thickness of each Co layer is 0.3nm-0.8nm, and the thickness of each Pd layer is 0.8nm-1.5nm.

When the [Co/Ni] _n multilayer film is used for the vertical magnetization film, the Co layer and the Ni layer are deposited periodically, the thickness of each Co layer is 0.3nm-0.8nm, and the thickness of each Ni layer is 0.8nm-1.5nm.

In the above embodiments, the thickness of the antiferromagnetic layer is 6 nm to 20 nm, and the antiferromagnetic layer is made of Mn-based alloys such as IrMn, FeMn, and PtMn or oxide antiferromagnetic materials such as NiO, Cr ₂ O ₃ , Sr ₂ IrO ₄ . kind of.

The present invention is based on the preparation method of the magnetic field detector of vertical exchange coupling, specifically comprises the following steps:

1) The bottom electrode 2, the ferromagnetic layer 3, the non-magnetic layer 4 and the top electrode 5 are sequentially deposited on the substrate 1 by magnetron sputtering or electron beam evaporation to obtain a multilayer film structure.

2) As shown in Figure 2, the multilayer film structure obtained in step 1) is processed into a cross ^- shaped structure by using processes such as ultraviolet exposure and argon ion etching. 600 μm ² , and the cross-overlapping portion at the center of the cross-shaped structure has an area of 5×3 μm ² to 40×30 μm ² .

As shown in FIG. 2 , the first to fourth endpoints of the magnetic field detector based on vertical exchange coupling of the present invention are respectively marked as a, b, c, and d. A current I is passed between the first terminal a and the second terminal b, and the Hall resistance R _Hall is measured between the third terminal c and the fourth terminal d.

The invention can use the sensitivity of the Hall signal of the vertical exchange coupling system to the magnitude and direction of the magnetic field to accurately judge the magnitude and direction of the magnetic field in an environment with a temperature range of 2K-400K. When the magnetic field detector of the present invention is used to detect the magnetic field, the Hall signal of the magnetic field detector is very sensitive to the direction of the magnetic field.

When the direction of the magnetic field is perpendicular to the plane of the magnetic field detector, the magnetic field detector has an abnormal Hall signal, that is, under the action of positive and negative magnetic fields, the Hall resistance measured between the third terminal c and the fourth terminal d has obvious high and low resistance state.

When the direction of the magnetic field is parallel to the plane of the magnetic field detector, the magnetic field detector has a planar Hall signal, that is, when the detected magnetic field is greater than the saturation magnetic field, under the action of positive and negative magnetic fields, the signal measured between the third terminal c and the fourth terminal d The Hall resistors are exactly the same size.

When the direction of the magnetic field is between perpendicular to and parallel to the plane of the magnetic field detector, the magnetic field detector has a superimposed signal of the abnormal Hall signal and the planar Hall signal. When the direction of the magnetic field deviates slightly from the plane of the magnetic field detector by 0.2°, the line shape of the Hall signal curve changes significantly.

In addition, by applying different voltages on the ferroelectric substrate, the size of the coercive force and the perpendicular magnetization performance of the ferromagnetic layer can be changed, that is, the size of the abnormal Hall signal switching field of the magnetic field detector can be changed, so that in the direction-determined magnetic field , under a fixed magnetic field, apply different voltages on the ferroelectric substrate, and record the voltage value when the Hall resistance changes. The coercive force of the vertical exchange coupling system corresponding to the voltage value at this time is the magnitude of the magnetic field.

Using the magnetic field detector based on vertical exchange coupling of the present invention to detect the magnetic field, it specifically includes the following steps:

1) Place the magnetic field detector in a magnetic field with unknown direction and magnitude;

2) Pass a current I between the first terminal a and the second terminal b, and measure the Hall resistance between the third terminal c and the fourth terminal d. Rotate the magnetic field detector to read the Hall resistance values under any six different magnetic field sizes at a certain angle. Among them, the Hall resistance values R ₁ , R ₂ and R ₃ under three positive magnetic fields; the Hall resistance values R ₄ , R ₅ and R ₆ under three negative magnetic fields, and according to the relationship between the Hall resistance values The relationship determines the direction of the magnetic field, which specifically includes:

If R ₁ =R ₂ =R ₃ =R ₄ =R ₅ =R ₆ , the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

If the values of the Hall resistances are different, record the average value k of the absolute values of the differences of the Hall resistances, rotate the magnetic field detector, and the value of k changes continuously. When the value of k becomes 0, that is, R ₁ =R ₂ = When R ₃ =R ₄ =R ₅ =R ₆ , stop rotating the magnetic field detector, and at this time, the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

The average value k of the absolute value of each Hall resistance difference is:

$\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; 15</span>}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 6</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; 6</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}<span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>$

3) For the magnetic field whose direction is determined in step 2), use the following two methods to determine the magnitude of the magnetic field:

method one:

①As shown in Figure 2, the surface of the magnetic field detector is taken as an xy plane, where the direction parallel to the current I flowing between the first end point a and the second end point b is the x-axis, and the direction perpendicular to the current I is The y axis uses the direction perpendicular to the xy plane as the z axis to establish a space coordinate system.

② Place the magnetic field detector in the magnetic field whose direction is determined in step 2), make the x-axis parallel to the direction of the magnetic field, rotate the magnetic field detector 360° around the z-axis, measure and record the Huo during the rotation of the magnetic field detector around the z-axis Hall resistance value; draw a resistance-angle curve according to the rotation angle of the magnetic field detector around the z-axis and the measured Hall resistance value.

③ Place the magnetic field detector in a number of magnetic fields with known directions and sizes, use the same method as step ① and step ②, draw several lines according to the angle of rotation of the magnetic field detector around the z-axis and the measured Hall resistance value Standard resistance-angle curve. The magnitude range of the magnetic field with known direction and magnitude is 0.01kOe～90kOe.

④ Compare a drawn resistance-angle curve with several standard resistance-angle curves, and find out the standard resistance-angle curve that is the same as the drawn resistance-angle curve. The magnetic field corresponding to this standard resistance-angle curve is is the size of the magnetic field to be determined.

Method Two:

Place the magnetic field detector with the ferroelectric substrate in a magnetic field of unknown magnitude, make the film surface of the magnetic field detector perpendicular to the direction of the magnetic field, apply a voltage varying from -10V to 10V on the ferroelectric substrate, and record the third terminal c The voltage value when the Hall resistance changes between the fourth terminal d and the coercive force of the vertical exchange coupling system corresponding to the voltage value at this time is the magnitude of the magnetic field.

Example 1: Prepare a magnetic field detector with Si/SiO ₂ /[Pt/Co] ₂ /IrMn/Pt from bottom to top, which specifically includes:

1) Using the magnetron sputtering method, a Pt bottom electrode 2, a [Pt/Co] ₂ ferromagnetic layer 3, an IrMn nonmagnetic layer 4 and a Pt top electrode 5 are sequentially deposited on a Si/SiO ₂ substrate 1 to obtain a multilayer Membrane structure.

Wherein, the thickness of the SiO ₂ layer in the Si/SiO ₂ substrate 1 is 200-400 nm. [Pt/Co] ₂ In the ferromagnetic layer 2, the Pt layer has a thickness of 1 nm, and the Co layer has a thickness of 0.5 nm. The thickness of the IrMn nonmagnetic layer 3 is 6 nm to 20 nm, preferably 8 nm.

2) Process the multilayer film structure into a cross-shaped structure by using ultraviolet exposure and argon ion etching. The area of the rectangle where the cross-shaped structure is located is 500×300μm ² to 1000×600μm ² , and the overlapping part of the center of the cross-shaped structure The area is 5×3 μm ² to 40×30 μm ² .

As shown in FIG. 1 , a current is passed between the first terminal a and the second terminal b of the magnetic field detector, and the Hall resistance R _Hall is measured between the third terminal c and the fourth terminal d of the magnetic field detector. Determine the direction and magnitude of the magnetic field using the following methods:

1) Place the magnetic field detector in a magnetic field with unknown direction and magnitude;

2) Rotate the magnetic field detector to read the Hall resistance values of any six different magnetic field sizes at a certain angle. Among them, the Hall resistance values R ₁ , R ₂ and R ₃ under three positive magnetic fields; the Hall resistance values R ₄ , R ₅ and R ₆ under three negative magnetic fields, and according to the relationship between the Hall resistance values The relationship determines the direction of the magnetic field, which specifically includes:

If R ₁ =R ₂ =R ₃ =R ₄ =R ₅ =R ₆ , the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

If the values of the Hall resistances are different, record the average value k of the absolute values of the differences of the Hall resistances, rotate the magnetic field detector, and the value of k changes continuously. When the value of k becomes 0, that is, R ₁ =R ₂ = When R ₃ =R ₄ =R ₅ =R ₆ , stop rotating the magnetic field detector, and at this time, the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

3) For the magnetic field whose direction is determined in step 2), use the following method to determine the magnitude of the magnetic field:

①As shown in Figure 2, the surface of the magnetic field detector is taken as an xy plane, where the direction parallel to the current I flowing between the first end point a and the second end point b is the x-axis, and the direction perpendicular to the current I is The y axis uses the direction perpendicular to the xy plane as the z axis to establish a space coordinate system.

② Place the magnetic field detector in the magnetic field whose direction is determined in step 2), make the x-axis parallel to the direction of the magnetic field, rotate the magnetic field detector 360° around the z-axis, measure and record the Huo during the rotation of the magnetic field detector around the z-axis Hall resistance value; draw a resistance-angle curve according to the rotation angle of the magnetic field detector around the z-axis and the measured Hall resistance value.

③ Place the magnetic field detector in a number of magnetic fields with known directions and sizes, use the same method as step ① and step ②, draw several lines according to the angle of rotation of the magnetic field detector around the z-axis and the measured Hall resistance value Standard resistance-angle curve. The magnitude range of the magnetic field with known direction and magnitude is 0.01kOe～90kOe.

④ Compare a drawn resistance-angle curve with several standard resistance-angle curves, and find out the standard resistance-angle curve that is the same as the drawn resistance-angle curve. The magnetic field corresponding to this standard resistance-angle curve is is the size of the magnetic field to be determined.

Example 2: Preparation of a magnetic field detector of MgO/CoFeB/FeMn/Pt from bottom to top

1) Using the method of magnetron sputtering, a Pt bottom electrode 2, a CoFeB ferromagnetic layer 3, a FeMn nonmagnetic layer 4 and a Pt top electrode 5 are sequentially deposited on the MgO substrate 1 to obtain a multilayer film structure.

Wherein, the CoFeB ferromagnetic layer 3 is a perpendicularly magnetized ferromagnetic layer with a thickness of 0.7-1.5 nm, preferably 1.2 nm. The thickness of the FeMn non-magnetic layer 4 is 6-20 nm, preferably 10 nm.

2) Process the multilayer film structure into a cross-shaped structure by using ultraviolet exposure and argon ion etching. The area of the rectangle where the cross-shaped structure is located is 500×300μm ² to 1000×600μm ² , and the overlapping part of the center of the cross-shaped structure The area is 5×3 μm ² to 40×30 μm ² .

As shown in FIG. 1 , a current is passed between the first terminal a and the second terminal b of the magnetic field detector, and the Hall resistance R _Hall is measured between the third terminal c and the fourth terminal d of the magnetic field detector. Determine the direction and magnitude of the magnetic field using the following methods:

1) Place the magnetic field detector in a magnetic field with unknown direction and magnitude;

2) Rotate the magnetic field detector to read the Hall resistance values of any six different magnetic field sizes at a certain angle. Among them, the Hall resistance values R ₁ , R ₂ and R ₃ under three positive magnetic fields; the Hall resistance values R ₄ , R ₅ and R ₆ under three negative magnetic fields, and according to the relationship between the Hall resistance values The relationship determines the direction of the magnetic field, which specifically includes:

If R ₁ =R ₂ =R ₃ =R ₄ =R ₅ =R ₆ , the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

If the values of the Hall resistances are different, record the average value k of the absolute values of the differences of the Hall resistances, rotate the magnetic field detector, and the value of k changes continuously. When the value of k becomes 0, that is, R ₁ =R ₂ = When R ₃ =R ₄ =R ₅ =R ₆ , stop rotating the magnetic field detector, and at this time, the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

3) For the magnetic field whose direction is determined in step 2), use the following method to determine the magnitude of the magnetic field:

①As shown in Figure 2, the surface of the magnetic field detector is taken as an xy plane, where the direction parallel to the current I flowing between the first end point a and the second end point b is the x-axis, and the direction perpendicular to the current I is The y axis uses the direction perpendicular to the xy plane as the z axis to establish a space coordinate system.

② Place the magnetic field detector in the magnetic field whose direction is determined in step 2), make the x-axis parallel to the direction of the magnetic field, rotate the magnetic field detector 360° around the z-axis, measure and record the Huo during the rotation of the magnetic field detector around the z-axis Hall resistance value; draw a resistance-angle curve according to the rotation angle of the magnetic field detector around the z-axis and the measured Hall resistance value.

③ Place the magnetic field detector in a number of magnetic fields with known directions and sizes, use the same method as step ① and step ②, draw several lines according to the angle of rotation of the magnetic field detector around the z-axis and the measured Hall resistance value Standard resistance-angle curve. The magnitude range of the magnetic field with known direction and magnitude is 0.01kOe～90kOe.

④ Compare a drawn resistance-angle curve with several standard resistance-angle curves, and find out the standard resistance-angle curve that is the same as the drawn resistance-angle curve. The magnetic field corresponding to this standard resistance-angle curve is is the size of the magnetic field to be determined.

Example 3: Preparation of a magnetic field detector of PZT/CoFeB/MgO/Pt from bottom to top

1) Using magnetron sputtering method, deposit Pt bottom electrode 2, CoFeB ferromagnetic layer 3, MgO non-magnetic layer 4 and Pt top electrode 5 sequentially on PZT ferroelectric substrate 1 to obtain a multilayer film structure.

Wherein, the CoFeB ferromagnetic layer 3 is a perpendicularly magnetized ferromagnetic layer with a thickness of 0.7-1.5 nm, preferably 1 nm. The thickness of the MgO non-magnetic layer 4 is 0.6-1.2 nm, preferably 0.8 nm.

2) Process the multilayer film structure into a cross-shaped structure by using ultraviolet exposure and argon ion etching. The area of the rectangle where the cross-shaped structure is located is 500×300μm ² to 1000×600μm ² , and the overlapping part of the center of the cross-shaped structure The area is 5×3 μm ² to 40×30 μm ² .

As shown in FIG. 1 , a current is passed between the first terminal a and the second terminal b of the magnetic field detector, and the Hall resistance R _Hall is measured between the third terminal c and the fourth terminal d of the magnetic field detector. Determine the direction and magnitude of the magnetic field using the following methods:

1) Place the magnetic field detector in a magnetic field with unknown direction and magnitude;

2) Rotate the magnetic field detector to read the Hall resistance values of any six different magnetic field sizes at a certain angle. Among them, the Hall resistance values R ₁ , R ₂ and R ₃ under three positive magnetic fields; the Hall resistance values R ₄ , R ₅ and R ₆ under three negative magnetic fields, and according to the relationship between the Hall resistance values The relationship determines the direction of the magnetic field, which specifically includes:

If R ₁ =R ₂ =R ₃ =R ₄ =R ₅ =R ₆ , the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

If the values of the Hall resistances are different, record the average value k of the absolute values of the differences of the Hall resistances, rotate the magnetic field detector, and the value of k changes continuously. When the value of k becomes 0, that is, R ₁ =R ₂ = When R ₃ =R ₄ =R ₅ =R ₆ , stop rotating the magnetic field detector, and at this time, the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

3) For the magnetic field whose direction is determined in step 2), use the following method to determine the magnitude of the magnetic field:

Place a magnetic field detector with a PZT ferroelectric substrate in a magnetic field of unknown magnitude, make the film surface of the magnetic field detector perpendicular to the direction of the magnetic field, apply a voltage varying from -10V to 10V on the ferroelectric substrate, and record the third endpoint The voltage value when the Hall resistance between c and the fourth terminal d changes, and the coercive force of the vertical exchange coupling system corresponding to the voltage value at this time is the magnitude of the magnetic field. Since the coercive force of CoFeB is controlled by ferroelectricity in a wide range, the prepared PZT/CoFeB/MgO/Pt magnetic field detector can be widely used in the detection of a large range of magnetic field.

Example 4: Preparation of a magnetic field detector of BaTiO ₃ /[Co/Ni] ₁₀ /NiO/Pt from bottom to top

1) Using the electron beam evaporation method, the Pt bottom electrode 2, [Co/Ni] ₁₀ ferromagnetic layer 3, NiO nonmagnetic layer 4 and Pt top electrode 5 are sequentially deposited on the BaTiO ₃ ferroelectric substrate 1 to obtain a multilayer Membrane structure.

Wherein, the [Co/Ni] ₁₀ ferromagnetic layer 3 is a ferromagnetic layer with perpendicular magnetization, the thickness of the Co layer is 0.3 nm, and the thickness of the Ni layer is 0.8 nm. The thickness of the NiO nonmagnetic layer 4 is 0.8 to 1.5 nm.

2) Process the multilayer film structure into a cross-shaped structure by using ultraviolet exposure and argon ion etching. The area of the rectangle where the cross-shaped structure is located is 500×300μm ² to 1000×600μm ² , and the overlapping part of the center of the cross-shaped structure The area is 5×3 μm ² to 40×30 μm ² .

As shown in FIG. 1 , a current is passed between the first terminal a and the second terminal b of the magnetic field detector, and the Hall resistance R _Hall is measured between the third terminal c and the fourth terminal d of the magnetic field detector. Determine the direction and magnitude of the magnetic field using the following methods:

1) Place the magnetic field detector in a magnetic field with unknown direction and magnitude;

2) Rotate the magnetic field detector to read the Hall resistance values of any six different magnetic field sizes at a certain angle. Among them, the Hall resistance values R ₁ , R ₂ and R ₃ under three positive magnetic fields; the Hall resistance values R ₄ , R ₅ and R ₆ under three negative magnetic fields, and according to the relationship between the Hall resistance values The relationship determines the direction of the magnetic field, which specifically includes:

If R ₁ =R ₂ =R ₃ =R ₄ =R ₅ =R ₆ , the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

If the values of the Hall resistances are different, record the average value k of the absolute values of the differences of the Hall resistances, rotate the magnetic field detector, and the value of k changes continuously. When the value of k becomes 0, that is, R ₁ =R ₂ = When R ₃ =R ₄ =R ₅ =R ₆ , stop rotating the magnetic field detector, and at this time, the direction parallel to the surface of the magnetic field detector is determined as the magnetic field direction.

3) For the magnetic field whose direction is determined in step 2), use the following method to determine its magnetic field size:

Place the detector with the BaTiO ₃ ferroelectric substrate in a magnetic field of unknown magnitude, make the film surface of the magnetic field detector perpendicular to the direction of the magnetic field, apply a voltage varying from -10V to 10V on the ferroelectric substrate, and record the third endpoint The voltage value when the Hall resistance between c and the fourth terminal d changes, and the coercive force of the vertical exchange coupling system corresponding to the voltage value at this time is the magnitude of the magnetic field. Since the coercive force of [Co/Ni] ₁₀ varies widely by ferroelectric control, the prepared BaTiO ₃ /[Co/Ni] ₁₀ /NiO/Pt magnetic field detector can be widely used in the detection of a large range of magnetic field.

The above-mentioned embodiments are only used to illustrate the present invention, wherein the structure, connection mode and method steps of each component can be changed to some extent, and any equivalent transformation and improvement carried out on the basis of the technical solution of the present invention should not be used. excluded from the protection scope of the present invention.

Claims (9)

1. a magnetic field detectors based on vertical exchange coupling, it is characterized in that: it includes substrate, hearth electrode, ferromagnetic layer, nonmagnetic layer and top electrode, described substrate uses decussate texture, described hearth electrode, ferromagnetic layer, nonmagnetic layer and top electrode are sequentially depositing on the substrate, and the shape of described hearth electrode, ferromagnetic layer, nonmagnetic layer and top electrode all with the shape of described substrate in mating setting；Described ferromagnetic layer is made up of vertical magnetized film, and described nonmagnetic layer is made up of inverse ferric magnetosphere or oxide layer, and described hearth electrode and top electrode all use Pt electrode.

A kind of magnetic field detectors based on vertical exchange coupling, it is characterised in that: the thickness of the nonmagnetic layer constituting oxide layer is 0.5nm～1.5nm.

A kind of magnetic field detectors based on vertical exchange coupling, it is characterised in that: described substrate uses Si (100)/SiO₂Common substrate, MgO monocrystal chip, SrTiO₃One in monocrystal chip and ferroelectric substrate, described ferroelectric substrate uses BaTiO₃, one in PZT and PMN-PT.

A kind of magnetic field detectors based on vertical exchange coupling, it is characterised in that: the vertical magnetized film constituting described ferromagnetic layer uses [Co/Pt] of perpendicular magnetization_nMultilayer film, [Co/Pd]_nMultilayer film, [Co/Ni]_nOne in multilayer film and CoFeB, n=1～10；

Vertical magnetized film uses [Co/Pt]_nDuring multilayer film, Co layer and Pt layer cycle repeated deposition, the thickness of each Co layer is 0.3nm～0.8nm, and the thickness of each Pt layer is 0.8nm～1.5nm；

Vertical magnetized film uses [Co/Pd]_nDuring multilayer film, Co layer and Pd layer cycle repeated deposition, the thickness of each Co layer is 0.3nm～0.8nm, and the thickness of each Pd layer is 0.8nm～1.5nm；

Vertical magnetized film uses [Co/Ni]_nDuring multilayer film, Co layer and Ni layer cycle repeated deposition, the thickness of each Co layer is 0.3nm～0.8nm, and the thickness of each Ni layer is 0.8nm～1.5nm；

When vertical magnetized film uses CoFeB, the thickness of CoFeB is 0.7nm～1.5nm.

A kind of magnetic field detectors based on vertical exchange coupling, it is characterised in that: the inverse ferric magnetosphere constituting described nonmagnetic layer uses a kind of Mn system alloy material in IrMn, FeMn and PtMn；Or the inverse ferric magnetosphere constituting described nonmagnetic layer uses NiO, Cr₂O₃And Sr₂IrO₄In a kind of oxide antiferromagnet.

6. a preparation method based on the vertical exchange coupled magnetic field detector as described in any one of Claims 1 to 5, it comprises the following steps:

1) use magnetron sputtering or electron beam evaporation methods, substrate is sequentially depositing hearth electrode, ferromagnetic layer, nonmagnetic layer and top electrode, obtains multi-layer film structure；

2) using uv-exposure and argon ion etching technique, the multi-layer film structure obtained is processed into a decussate texture, the area of decussate texture place rectangle is 500 × 300 μm²～1000 × 600 μm², the area of the cross-coincidence part at decussate texture center is 5 × 3 μm²～40 × 30 μm²。

7. a using method based on the vertical exchange coupled magnetic field detector as described in any one of claim 1～6, it comprises the following steps:

1) magnetic field detectors is placed in the magnetic field of direction and size all the unknowns；

2) galvanization I between the first end points and the second end points, surveys Hall resistance between the 3rd end points and the 4th end points；Rotary magnetic field detector, reads the resistance value under any six different magnetic field sizes under a certain angle respectively；Wherein, Hall resistance value R under three positive flux fields₁、R₂And R₃；Hall resistance value R under three negative fluxfields₄、R₅And R₆, and determine magnetic direction according to the relation between each Hall resistance value；

3) to step 2) in the magnetic field that determines, direction, use following steps to determine size:

1. using the surface of magnetic field detectors as x/y plane, wherein, being parallel to the direction of institute galvanization I between the first end points and the second end points is x-axis, and the direction being perpendicular to electric current I is y-axis, using the direction vertical with x/y plane as z-axis, sets up space coordinates；

2. magnetic field detectors is placed on step 2) in the magnetic field that determines, direction, make x-axis be parallel to this magnetic direction, by magnetic field detectors around z-axis rotating 360 degrees, measure and recording magnetic field detector Hall resistance value in z-axis rotary course；The Hall resistance value that the angle rotated around z-axis according to magnetic field detectors and measurement obtain, draws a resistance-angle curve；

3. magnetic field detectors is placed in magnetic field known to some directions and size, uses with step 1. and the Hall resistance value that obtains of the most identical method of step, the angle rotated around z-axis according to magnetic field detectors and measurement, draw some measuring resistance-angle curve；

4. resistance-the angle curve drawn is compared with some measuring resistance-angle curve, measuring resistance-angle curve that resistance-angle curve of finding out and draw is identical, the magnetic field size that this measuring resistance-angle curve is corresponding is the size in this magnetic field to be determined.

8. the using method of the magnetic field detectors coupled based on vertical exchange as claimed in claim 7, it is characterised in that: described step 3) in, known to direction and size, its magnitude range of magnetic field is 0.01kOe～90kOe.

9. the using method of magnetic field detectors based on vertical exchange coupling as described in any one of claim 1～6, it comprises the following steps:

1) magnetic field detectors is placed in the magnetic field of direction and size all the unknowns；

2) galvanization I between the first end points and the second end points, surveys Hall resistance between the 3rd end points and the 4th end points；Rotary magnetic field detector, reads the Hall resistance value under any six different magnetic field sizes, wherein, Hall resistance value R under three positive flux fields under a certain angle respectively₁、R₂And R₃；Hall resistance value R under three negative fluxfields₄、R₅And R₆, and determine magnetic direction according to the relation between each Hall resistance value；

3) to step 2) in the magnetic field that determines, direction, determine that the process of its magnetic field size is:

Magnetic field detectors with ferroelectric substrate is placed in the magnetic field of unknown size, magnetic direction is allowed to be perpendicular to the film surface of magnetic field detectors, ferroelectric substrate applies the voltage of-10V～10V change, recording Hall resistance between the 3rd end points and the 4th end points and magnitude of voltage when changing occurs, the coercivity of this vertical exchange Fourier Series expansion technique that magnitude of voltage now is corresponding is the size in magnetic field.