阅读说明：本技术 钴基Heusler合金结构及提升其有序化的制备方法 (Cobalt-based Heusler alloy structure and preparation method for improving ordering of cobalt-based Heusler alloy structure ) 是由 陈嘉民 邹旭东 薛宁 祁志美 于 2020-05-13 设计创作，主要内容包括：一种提升钴基Heusler合金结构有序化的制备方法,包括以下步骤：样品基板清洗；低蒸汽压元素与钴基Heusler合金进行共溅射成膜；高真空退火处理。本发明提出了使用低蒸汽压元素掺杂后退火的方法来提高钴基Heusler合金薄膜材料的性能,使其具有高结晶度、低温有序化、高自旋极化率的优点。(A preparation method for improving structural ordering of a cobalt-based Heusler alloy comprises the following steps: cleaning a sample substrate; co-sputtering the low vapor pressure element and the cobalt-based Heusler alloy to form a film; and (5) high vacuum annealing treatment. The invention provides a method for annealing after doping low-vapor-pressure elements to improve the performance of a cobalt-based Heusler alloy film material, so that the cobalt-based Heusler alloy film material has the advantages of high crystallinity, low-temperature ordering and high spin polarization rate.)

1. A preparation method for improving the structural ordering of a cobalt-based Heusler alloy is characterized by comprising the following steps of:

cleaning a sample substrate;

co-sputtering the low vapor pressure element and the cobalt-based Heusler alloy to form a film;

and (5) high vacuum annealing treatment.

2. The method as claimed in claim 1, wherein in the step of cleaning the sample substrate, the sample substrate is sequentially cleaned by ultrasonic cleaning with acetone, alcohol and deionized water for 3-10 minutes, and after the ultrasonic cleaning, the sample substrate is placed in a vacuum chamber of a magnetron sputtering apparatus for thermal cleaning at 500-800 ℃.

3. The method of claim 1, wherein the low vapor pressure element is a zinc, magnesium, mercury, sodium, potassium, silver, gold, copper, or titanium element.

4. The method according to claim 1, wherein the co-sputtering of the low vapor pressure element and the cobalt-based Heusler alloy to form the film specifically comprises the steps of: the cobalt-based Heusler alloy thin film material doped with the low-vapor-pressure element is prepared on a sample substrate by using a cobalt-based Heusler alloy target and a low-vapor-pressure element simple substance target and utilizing a confocal magnetron sputtering method.

5. The method according to claim 4, wherein the properties of the thin film material and the doping concentration of the low vapor pressure element are controlled by parameters of sputtering time, sputtering temperature, sputtering power, power type, process gas pressure, flow rate, size of mesh of the barrier net, and target-sample distance in the magnetron sputtering process.

6. The method according to claim 1, wherein in the step of high vacuum annealing, the thin film material is prepared under a vacuum degree of 10^-6-10^-8And annealing treatment is carried out in the ultra-high vacuum sputtering chamber of pa at the temperature of 300-600 ℃, wherein the annealing time is 10-120 minutes.

7. The manufacturing method according to claim 1, wherein the manufacturing method can be extended to all cobalt-iron (Co) bases₂Fe-based), cobalt manganese (Co) based₂Mn-based) Heusler alloy material system.

8. A cobalt-based Heusler alloy thin film material prepared according to the preparation method as set forth in any one of claims 1 to 7.

9. The cobalt-based Heusler alloy thin film material of claim 8, wherein the cobalt-based Heusler alloy thin film material can be used in the fabrication of spintronic devices for improving the performance of hard disk magnetic heads, magnetic random access memories, magnetic sensors, or spin logic circuit products.

Technical Field

The invention relates to the technical field of electronic device preparation, in particular to a cobalt-based Heusler alloy structure and a preparation method for improving the ordering of the cobalt-based Heusler alloy structure.

Background

Spintronics devices such as giant magnetoresistive (gmr) devices, tunneling magnetoresistive (tmr) devices, and tunneling magnetoresistive (tunneling magnetoresistive) devices are widely used in information technology fields such as hard disk magnetic heads of computers, memories, and sensors for industrial control. With the rapid development of big data and internet of things technology, the demands for rapid, efficient and low-power-consumption acquisition, storage and calculation of massive information data are increasing. To meet this demand, development of next-generation higher-performance spintronic devices is urgently required. The development of thin film materials with high spin polarizability characteristics, such as Heusler/Heusler alloys (Heusler alloys), is the key point for preparing high performance spintronic devices.

Heusler alloy is a class of intermetallic compounds that was first discovered by f.heulser in 1903. At that time he found Cu₂The elements in MnAl are all non-ferromagnetic elements, but the compound shows ferromagnetism. Heusler alloys with highly ordered structures exhibit very rich physical properties, with a variety of application functions, such as half-metallic properties, ferromagnetism, thermoelectric effects, magnetoresistive effects, superconductivity, shape memory effects, etc. Heusler alloy can be divided into two major categories, half-Heusler and full-Heusler, and is a large alloy family, as shown in fig. 1. The cobalt-based full-Heusler alloy is favored by researchers due to the characteristics of high spin polarization rate, high Curie temperature, low damping factor, good lattice matching degree with substrates such as GaAs and MgO and the like.

Since the semimetal characteristic of cobalt-based Heusler alloy (the semimetal characteristic means that the material has only electrons in one spin direction near the fermi surface of the band structure, and thus theoretically has 100% spin polarizability), efforts have been made to search for new cobalt-based Heusler alloy materials having 100% high spin polarizability at room temperature and practically applicable to spintronic devices.

At present, in the reported cobalt-based Heusler alloy thin film material with high spin polarizability, it is generally required to obtain ordered L2 by high temperature annealing (above 500 ℃ C.) process₁Crystal structure, thereby improving the spin polarizability of the thin film material. However, high temperature annealing processes above 500 degrees Celsius are applied to spintronsThe preparation of the device is over high in temperature, is incompatible with the current silicon-based device manufacturing process, and seriously limits the application of the high-spin-polarization-rate cobalt-based Heusler alloy thin film material in the preparation of high-performance spin electronic devices. Therefore, it is necessary to develop a new process to solve the problems caused by high temperature annealing.

Disclosure of Invention

In view of the above, the main objective of the present invention is to provide a preparation method for improving the structural ordering of a cobalt-based Heusler alloy, so as to partially solve at least one of the above technical problems.

In order to achieve the above objects, as one aspect of the present invention, there is provided a preparation method for improving structural ordering of a cobalt-based Heusler alloy, comprising the steps of:

cleaning a sample substrate;

co-sputtering the low vapor pressure element and the cobalt-based Heusler alloy to form a film;

and (5) high vacuum annealing treatment.

In the step of cleaning the sample substrate, the sample substrate is sequentially subjected to ultrasonic cleaning by using acetone, alcohol and deionized water for 3-10 minutes, and after the ultrasonic cleaning is finished, the sample substrate is placed into a vacuum chamber of a magnetron sputtering instrument for thermal cleaning at the temperature of 500-.

Wherein the low vapor pressure element is zinc, magnesium, mercury, sodium, potassium, silver, gold, copper or titanium.

The co-sputtering film formation of the low vapor pressure element and the cobalt-based Heusler alloy specifically comprises the following steps: the cobalt-based Heusler alloy thin film material doped with the low-vapor-pressure element is prepared on a sample substrate by using a cobalt-based Heusler alloy target and a low-vapor-pressure element simple substance target and utilizing a confocal magnetron sputtering method.

The performance of the film material and the doping concentration of the low-vapor-pressure element are regulated and controlled by parameters of sputtering time, sputtering temperature, sputtering power, power type, process gas pressure, flow rate, sputtering power, mesh size of the blocking net and target-sample distance in the magnetron sputtering process.

Wherein the high vacuumIn the annealing treatment step, the prepared film material has the vacuum degree of 10^-6-10^{- 8}And (3) annealing treatment at 300-600 ℃ is carried out in an ultrahigh vacuum sputtering chamber of Pa, and the annealing time is 10-120 minutes.

Wherein, the preparation method can be widely applied to all cobalt-iron (Co) bases₂Fe-based), cobalt manganese (Co) based₂Mn-based) Heusler alloy material system.

As another aspect of the present invention, there is provided a cobalt-based Heusler alloy structure manufactured using the manufacturing method as described above.

The cobalt-based Heusler alloy thin film material can be used for preparing a spin electronic device and is used for improving the performance of a hard disk magnetic head, a magnetic random access memory, a magnetic sensor or a spin logic circuit product.

Based on the technical scheme, compared with the prior art, the preparation method for improving the structural ordering of the cobalt-based Heusler alloy has at least one of the following beneficial effects:

1. the invention provides a method for annealing after doping low-vapor-pressure elements to improve the performance of a cobalt-based Heusler alloy film material, so that the cobalt-based Heusler alloy film material has the advantages of high crystallinity, low-temperature ordering and high spin polarization rate.

2. The method for improving the performance of the film material by annealing after doping the low-vapor-pressure element can be widely applied to all cobalt-iron (Co-Fe) based materials₂Fe-based), cobalt manganese (Co) based₂Mn-based) Heusler alloy material system.

3. The high-performance cobalt-based Heusler alloy thin film material prepared by the invention can be used for preparing high-performance spin electronic devices and improving the performance of products such as hard disk magnetic heads, magnetic random access memories, magnetic sensors, spin logic circuits and the like.

Drawings

FIG. 1 is a periodic Table of elements of a Heusler alloy;

FIG. 2 is a flow chart of a method of making an embodiment of the present invention;

FIG. 3 is a schematic diagram of a co-sputter film of a low vapor pressure element and a cobalt-based Heusler alloy in accordance with an embodiment of the present invention;

FIG. 4 is a sectional structural view of a sample of a thin film material prepared according to a preparation method of an embodiment of the present invention;

FIG. 5 shows Co with different doping concentrations of Zn element₂FeGa_0.5Ge_0.5L2 for films at different annealing temperatures₁A graph of lattice order;

FIG. 6 shows Co prepared under different sputtering conditions₂FeGa_0.5Ge_0.5The content of zinc element of the film changes under different annealing temperatures.

Detailed Description

The high-performance cobalt-based Heusler alloy thin film material can be prepared by carrying out doping and high-vacuum annealing process treatment on the cobalt-based Heusler alloy (Heusler alloy) by using elements with low vapor pressure characteristics, has the advantages of high crystallinity, low-temperature ordering and high spin polarization rate, and can provide a material basis for the preparation of high-performance spin electronic devices.

In previous studies, high temperature annealing (above 500 degrees celsius) processes were typically used to obtain highly ordered lattices with L2₁A cobalt-based Heusler alloy thin film material with a crystal structure. In the invention, the inventor researches and discovers that a high-performance cobalt-based Heusler alloy thin film material can be prepared and obtained by carrying out co-sputtering doping on a cobalt-based Heusler alloy by using low-vapor-pressure elements (zinc, magnesium, mercury, sodium, potassium, silver, gold, copper, titanium and the like) and then carrying out annealing treatment in a high vacuum environment, and the thin film material has the advantages of high crystallinity, low-temperature ordering and high spin polarization rate, and can provide a material basis for the preparation of a high-performance spin electronic device. The specific preparation process is shown in figure 2.

In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.

1. Sample substrate cleaning

The sample substrate was ultrasonically cleaned with acetone, alcohol, and deionized water for 5 minutes each in this order. And after the cleaning, putting the cleaned product into a vacuum chamber of a magnetron sputtering instrument for thermal cleaning at 600 ℃.

2. Co-sputtering film formation with low vapor pressure element and Co-based Heusler alloy

As shown in FIG. 3, the co-sputtering film formation of the low vapor pressure element and the cobalt-based Heusler alloy comprises the following steps: the cobalt-based Heusler alloy thin film material doped with the low-vapor-pressure element is prepared on a sample substrate by using a cobalt-based Heusler alloy target and a low-vapor-pressure element simple substance target and utilizing a confocal magnetron sputtering method. The thickness of the film and the doping concentration of the low-vapor-pressure element are regulated and controlled by parameters such as sputtering time, sputtering temperature, sputtering power, power type, process gas pressure, flow rate, sputtering power, mesh size of a barrier net, target-sample distance and the like in the magnetron sputtering process.

3. High vacuum annealing treatment

The prepared film sample has a vacuum degree of 10^-7And (3) annealing treatment at 500 ℃ in an ultrahigh vacuum sputtering chamber of Pa for 30 minutes.

As shown in fig. 4, a cross-sectional structure view of a sample of the high-performance cobalt-based Heusler alloy thin film material prepared by the above-described method is shown.

In a further embodiment of the invention, Co is enhanced by elemental doping with zinc₂FeGa_0.5Ge_0.5(CFGG for short) the performance of the Heusler film material.

As shown in FIG. 5, as the doping concentration of Zn element increases, the crystallinity of CFGG film becomes better and better, and L2 of CFGG film₁The ordering anneal temperature of the crystal lattice is reduced. Such as L2 in 0%, 1.1% and 4.8% samples doped with zinc₁Ordering temperature of the lattice is 600 degrees Celsius, and L2 at 12.8% doping₁The ordering temperature of the lattice was lowered to 500 degrees celsius and further to 400 degrees celsius when 17.9% and 43.9% doped.

As shown in FIG. 6, as the annealing temperature increases, the zinc element in the CFGG film gradually precipitates out of the sample at 600 degrees Celsius for 30 minutes and 10 minutes^-7Under the annealing condition of Pa, the doped zinc element is almost completely separated out before annealing and escapes from the sample. Tong (Chinese character of 'tong')The method for improving the crystallinity, the lattice ordering degree and the spin polarizability of the Heusler alloy thin film material by precipitation and evaporation of the zinc element has not been reported previously.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.