RU2531516C2 - System for production of nanofilms of heusler alloys - Google Patents

Abstract

FIELD: nanotechnology.

SUBSTANCE: invention relates to the field of production of nanofilms of Heusler alloys, and due to the presence in them of great magnetocaloric effect it can be used for research and creation of a working body of eco-friendly and highly efficient refrigerators and heat pumps operating near room temperature. In the system for manufacturing nanofilms of Heusler alloys the film deposition on the substrate is carried out in the ultrahigh vacuum using two Nd:YAG lasers by simultaneous pulsed laser deposition from three separate targets made of pure materials.

EFFECT: providing the ability of rapid production of nanofilms of Heusler alloys of the desired (arbitrary) composition.

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Description

The invention relates to the field of production of nanofilms of Geisler alloys and, due to the presence of a large magnetocaloric effect (FEM) in them, can be used to study and create a working fluid for environmentally friendly and highly efficient refrigerators and heat pumps operating near room temperature. The use of nanofilms can significantly increase the frequency of the magnetic refrigerator. In addition, FEM in nanofilms is observed in lower magnetic fields (compared to bulk materials).

A known system for producing nanofilms of Geisler alloys by pulsed laser deposition (PLD) (ES Demidov et al. Nanoscale layers of ferromagnetic semiconductors and Geisler alloys based on silicon, germanium and 3d metals deposited from a laser plasma (Phase transitions, ordered states and new materials, 2010, No. 7 (4) http://www.ptosnm.ru/_files/ Moduls / catalog / items / T_catalog_items_F_download_I_572_v1.pdf), created on the basis of the laser system LQ529 “Solar LS.” In the system, thin-film deposition occurs as a result of sputtering a target made of Ge alloy slera by a pulsed Nd: YAG laser.

The disadvantage of the system is the need for preliminary manufacture of a target from a Geisler alloy (ternary alloys formed by metal atoms with a certain structure of electronic shells) of the exact composition from which the film is to be obtained, as well as the delay caused by the need to place a new target in the spray chamber and create the necessary for the deposition of ultra-high vacuum, and therefore it is impossible to quickly produce a Geisler film with the required (arbitrary) concentration of elements.

The technical result, to which the invention is directed, is the creation of a system that provides the ability to quickly produce nanofilms of Geisler alloys of the desired (arbitrary) composition.

The technical result is achieved in a system for manufacturing nanofilms of Heisler alloys, in which the film is deposited on a substrate in ultrahigh vacuum using two Nd: YAG lasers by simultaneous PLD from three separate targets made of pure materials. In this case, the PLA of a target made of Ni is carried out using the first laser with a wavelength of 532 nm, and the PLA of two other targets by alternately directing the radiation of a second laser at a wavelength of 266 nm on the target. The ability to control the repetition rate and pulse energy makes it possible to accurately control the stoichiometric composition of the resulting sample.

Figure 1 shows a diagram of a system for the manufacture of nanofilms of Geisler alloys: a - sectional side view of the system, b - top view of the system. 1 — loading chamber, 2 — magnetic rod, 3 — ultrahigh-vacuum gate, 4 — growth chamber, 5 — substrates on a substrate mounting system with a heater, 6 — targets on a target mounting system, 7 — optical path, 8 — Nd: YAG laser, 9 - Nd: YAG laser, 10 - system of rotation and change of position of the substrate.

The invention is as follows. The system includes a loading chamber 1, a magnetic rod 2 for supplying 4 substrates 5, fixed in the substrate mounting system with a heater, and targets 6 fixed in the target mounting system, through the ultra-high vacuum gate 3 to the growth chamber, through the optical path 7 laser radiation 8 is supplied into the system and laser 9, the position of the substrates 5 can be changed relative to the targets 6 using the rotation system 10. The position of the laser radiation beams on the targets can be changed using control mirrors 11, made with the ability to quickly adjust forward rotation around mutually perpendicular axes. The thickness control of the films is carried out using a system for observing the diffraction of reflected high-energy electrons 12. The growth chamber is inflated only in case of repair or routine maintenance, which allows you to always maintain a high vacuum up to 10 ^-11 Topp. The preliminary and main chambers have independent pumping systems, consisting of foreline and turbomolecular pumps. After pumping the preliminary chamber to a vacuum no worse than 5 × 10 ^-8 Topp, the substrates and targets are introduced into the growth chamber with the help of magnetic rod 2 and fixed in the fastening systems of the sample and targets. The targets that are not used during the process are located under the protective cover, which eliminates their dusting. The laser radiation is introduced into the camera using optical paths 7. Using these paths, radiation is introduced into the camera, it is focused on the target surface, and a laser beam is scanned along its surface.

The system can be implemented using standard technical solutions. In particular, the system is implemented by supplementing with another serial Nd: YAG laser the installation for pulsed laser deposition of films Smart Nano Tool PLD (http://www.svta.com/pulsed-laser-deposition-systems.html) with the corresponding mirror rotation systems to control the incidence of laser beams on the target.

Examples of the deposition of the Geisler alloy Ni-Mn-In are given. One of the lasers illuminates one target, the beam of another laser with the help of controlled rotary mirrors quickly moves from the second target to the third and back. In examples 1-3, the concentration of the elements deposited on the substrate is controlled by changing the ratio of the duration of the pulses on the targets. In examples 4, 5, the concentration of elements deposited on the substrate is controlled by a change in the energy of the laser pulse. Moreover, for the manufacture of any compositions of nanofilms of Geisler alloys, it is not necessary to produce a new target of the required composition, just as it is not necessary to depressurize the system to accommodate this target.

Example 1

Laser 8 illuminates In and Mn targets, wavelength 266 nm, pump lamp energy 31 J, delay 140 μs, pulse energy ~ 40 mJ, number of pulses 20,000, 5 pulses / sec. Of these, the number of pulses is 11700 directed to the Mn target, and 8300 pulses to the In target.

Laser 9: Ni target, wavelength 532 nm, pump lamp energy 15.5 J, delay 110 μs, pulse energy ~ 78 mJ, number of pulses 100000, 25 pulses / sec.

A film with a thickness of 50 nm of the composition Ni52Mn32In16 was formed on the substrate.

Example 2

Laser 8 illuminates In and Mn targets, wavelength 266 nm, pump lamp energy 31 J, delay 140 μs, pulse energy ~ 40 mJ, number of pulses 20,000, 5 pulses / sec. Of these, 11000 pulses were directed to the Mn target, and 9000 pulses were directed to the In target.

Laser 9: Ni target, wavelength 532 nm, pump lamp energy 15.5 J, delay 110 μs, pulse energy ~ 78 mJ, number of pulses 100000, 25 pulses / sec.

A 50 nm thick film of the composition Ni52Mn35In13 was formed on the substrate.

Example 3

Laser 8 illuminates In and Mn targets, wavelength 266 nm, pump lamp energy 31 J, delay 140 μs, pulse energy ~ 40 mJ, number of pulses 20,000, 5 pulses / sec. Of these, 12,900 pulses were directed to the Mn target, and 7,100 pulses to the In target.

Laser 9: Ni target, wavelength 532 nm, pump lamp energy 15.5 J, delay 110 μs, pulse energy ~ 78 mJ, number of pulses 100000, 25 pulses / sec.

A film with a thickness of 50 nm of the composition Ni52Mn38In10 was formed on the substrate.

Example 4

Laser 8 illuminates the In target, wavelength 266 nm, pump lamp energy 29.5 J, delay 140 μs, pulse energy ~ 40 mJ, number of pulses 20,000, 5 pulses / sec.

Laser 9: Ni + Mn targets, wavelength 532 nm, pump lamp energy 15.5 J, delay 110 μs, pulse energy ~ 78 mJ, number of pulses 100000, 25 pulses / sec. Of these, 25700 pulses are directed to the Mn target, and 74300 pulses to the Ni target.

A 50 nm thick film of the composition Ni57Mn26In17 was formed on the substrate.

Example 5

Laser 8 illuminates the In target, wavelength 266 nm, pump lamp energy 31.5 J, delay 140 μs, pulse energy ~ 40 mJ, number of pulses 20,000, 5 pulses / sec.

Laser 9: Ni + Mn targets, wavelength 532 nm, pump lamp energy 15.5 J, delay 110 μs, pulse energy ~ 78 mJ, number of pulses 100000, 25 imp / s. Of these, 25700 pulses are directed to the Mn target, and 74300 pulses to the Ni target.

A 50 nm thick film of the composition Ni52Mn23In25 was formed on the substrate.

The implementation of the system allows to obtain the claimed technical result, provides the possibility of rapid production of nanofilms of Geisler alloys of the required (arbitrary) composition. As shown in the examples, in the system, it is possible to manufacture any compositions of nanofilms of Geisler alloys, without the need to produce a new target of the required composition, just as it is not necessary to depressurize the system to accommodate this target.

Claims (1)

A system for producing nanofilms of Geisler alloys containing a loading chamber, a growth chamber, a magnetic rod for feeding substrates and targets into it through an ultrahigh-vacuum gate mounted in the substrate and target attachment systems, respectively, as well as an Nd: YAG laser installed with the possibility of supplying radiation to the target through the optical path, characterized in that the system includes at least one more Nd: YAG laser installed with the possibility of supplying radiation to other targets, as well as controlled mirrors made with the ability to quickly change the position of laser beams on targets, while the formation of Geisler alloy nanofilms on a substrate by two lasers is provided by simultaneous pulsed laser deposition of three targets made of Ni, Mn, and In, respectively.