阅读说明：本技术 具有高居里温度的ⅰ-ⅱ-ⅴ族稀磁半导体材料及其制备方法 (I-II-V family diluted magnetic semiconductor material with high Curie temperature and preparation method thereof ) 是由 毋志民 李越 丁守兵 罗一瑛 李可心 于 2021-01-18 设计创作，主要内容包括：本发明公开了一种具有高居里温度的Ⅰ-Ⅱ-Ⅴ族稀磁半导体材料,所述稀磁半导体材料是以LiCdAs为本征体,在Cd离子位等价掺杂Mn的多晶材料；是一种可通过电荷与自旋分离调控的新型稀磁半导体。该材料除了居里温度可达318K外,还具有优异的磁电性质,表现出明显的铁磁有序性。本发明的半导体材料制备方法简单,通过在Cd离子位等价掺杂Mn离子克服了化学固溶度的问题；通过Li离子化学计量数的调节可成功调控载流子浓度。当掺杂浓度为6％时,饱和磁矩达3.69μ-B/Mn,自发磁矩达0.32μ-B/Mn。材料具有20～40Oe的小矫顽力,且导电性能随掺杂浓度的升高而减弱,电阻率在掺杂浓度为15％时接近30Ω·cm。(The invention discloses an I-II-V family diluted magnetic semiconductor material with high Curie temperature, which is a polycrystalline material with LiCDAs as an intrinsic body and Mn equivalently doped at Cd ion site; the diluted magnetic semiconductor is a novel diluted magnetic semiconductor which can be regulated and controlled through charge and spin separation. Besides the Curie temperature of 318K, the material also has excellent magnetoelectric properties and shows obvious ferromagnetic order. The preparation method of the semiconductor material is simple, and the problem of chemical solid solubility is solved by equivalently doping Mn ions at the Cd ion site; the carrier concentration can be successfully regulated and controlled by adjusting the stoichiometric number of the Li ions. When the doping concentration is 6%, the saturation magnetic moment reaches 3.69 mu B Mn, spontaneous magnetic moment up to 0.32 mu B and/Mn. The material has a small coercive force of 20-40Oe, the conductivity is weakened along with the increase of doping concentration, and the resistivity is close to 30 omega cm when the doping concentration is 15%.)

1. A group i-ii-v diluted magnetic semiconductor material having a high curie temperature, comprising: the diluted magnetic semiconductor material is a polycrystalline material which takes LiCDAs as an intrinsic body and is equivalently doped with Mn at a Cd ion site.

2. The i-ii-v diluted magnetic semiconductor material with high curie temperature of claim 1, wherein: the diluted magnetic semiconductor material has a chemical formula of Li_1.04(Cd_1-x,Mn_x) As, wherein x is 0 to 0.15.

3. The i-ii-v diluted magnetic semiconductor material with high curie temperature of claim 2, wherein: the Li_1.04(Cd_1-x,Mn_x) X in As is 0, 0.02, 0.04, 0.06, 0.08, 0.10 or 0.15.

4. The i-ii-v diluted magnetic semiconductor material with high curie temperature of claim 3, wherein: the diluted magnetic semiconductor material has a cubic crystal structure.

5. The I-II-V diluted magnetic semiconductor material with high Curie temperature according to claim 4, wherein: the space group of the diluted magnetic semiconductor material is F-43 m.

6. A preparation method of I-II-V family diluted magnetic semiconductor material with high Curie temperature is characterized in that: and (3) carrying out high-temperature sintering treatment on the simple substance mixture of Li, Cd, As and Mn.

7. The method for preparing a group I-II-V diluted magnetic semiconductor material with high Curie temperature according to claim 6, wherein: the method comprises the following steps:

a. according to the chemical formula Li_1.04(Cd_1-x,Mn_x) The stoichiometric ratio of As is obtained by mixing Li flakes, Cd powder, As powder and Mn powder with the purity of more than or equal to 99.99 percent in water and oxygen concentration<Mixing under vacuum of 0.01 ppm;

b. sealing and vacuumizing the elementary substance mixture;

c. placing the sealed elementary substance mixture in a high-temperature heating furnace, firstly heating to 180-230 ℃ and keeping the temperature for 23-25h, then heating to 500-600 ℃ and keeping the temperature for 58-62h, then heating to 650-700 ℃ and keeping the temperature for 55-70h, finally cooling to 180-230 ℃ and naturally cooling to room temperature.

8. The method of claim 7, wherein the method comprises the steps of: in step b, the monomer mixture is placed in a quartz test tube and pumped 10 by a tube sealing machine^-4After high vacuum, Tour is sealed and sealed.

9. The method of claim 7, wherein the method comprises the steps of: in step c, the heating rate and the cooling rate are both 0.3-0.7 ℃/min.

10. The method of claim 9, wherein the method comprises the steps of: heating to 200 ℃ at a heating rate of 0.5 ℃/min and keeping the temperature for 24 hours, then heating to 540 ℃ at the same heating rate and keeping the temperature for 60 hours, then heating to 680 ℃ at the same heating rate and keeping the temperature for 55-70 hours, finally cooling to 200 ℃ at a cooling rate of 0.5 ℃/min and naturally cooling to room temperature.

Technical Field

The invention relates to a diluted magnetic semiconductor material, in particular to an I-II-V family diluted magnetic semiconductor material with high Curie temperature and a preparation method thereof.

Background

A Diluted Magnetic Semiconductor (DMS) may also be called a semi-Magnetic Semiconductor (SMS), which is called a Diluted Magnetic Semiconductor because the Magnetic elements in the DMS are relatively less compared to the common Magnetic materials, and because a trace amount of Magnetic atoms are introduced into a non-Magnetic Semiconductor, some micro mechanisms in the original Semiconductor, including the band structure and the behavior of carriers, are changed, so that the novel DMS has excellent and unique properties in the aspects of electricity, light, and magnetism. Unlike conventional DMS, the novel I-II-V group DMS not only can realize the separation and injection of charges and spins, but also can be used for preparing a block material, constructing a heterojunction, increasing the solid solubility of magnetic ions and improving the Curie Temperature (T Temperature)_c) And the like, and the method has great improvement and development. Therefore, the novel I-II-V group-based DMS material has important research significance and wide application prospect. At present, T exists in the second generation DMS, the third generation DMS or the novel I-II-V family DMS_cDefects below room temperature. In 2005, the SCIENCE journal presented 125 important scientific questions of "challenging the cognitive limits of humans", of which the scientific question of "being able to achieve room temperature magnetic semiconductors" was at the forefront in material SCIENCE. And so far, in the materials of II-VI group DMS and III-V group DMS, room temperature ferromagnetism appears in only ZnO and CaN, but the origin and mechanism of the magnetism are extremely controversial. Thus, enhancement of DMS materials or discovery of more T of novel group I-II-V DMS materials_cMaking it even higher than room temperature, further understanding the origin and mechanism of magnetism, and thus regulating room temperature ferromagnetism has been the direction of efforts of researchers.

Disclosure of Invention

In view of the above, the present invention aims to provide a novel diluted magnetic semiconductor material with high curie temperature, which can be controlled by charge and spin separation, and has excellent magnetoelectric properties and obvious ferromagnetic ordering, besides curie temperature up to 318K, and a preparation method thereof.

The I-II-V family diluted magnetic semiconductor material with high Curie temperature is a polycrystalline material which takes LiCDAs as an intrinsic body and is equivalently doped with Mn at a Cd ion site;

further, the diluted magnetic semiconductor material has a chemical formula of Li_1.04(Cd_1-x,Mn_x) As, wherein x is 0-0.15;

further, the Li_1.04(Cd_1-x,Mn_x) X in As is 0, 0.02, 0.04, 0.06, 0.08, 0.10 or 0.15;

further, the diluted magnetic semiconductor material is of a cubic crystal structure;

furthermore, the space group of the diluted magnetic semiconductor material is F-43 m.

The invention discloses a preparation method of an I-II-V family diluted magnetic semiconductor material with high Curie temperature, which comprises the following steps of carrying out high-temperature sintering treatment on a simple substance mixture of Li, Cd, As and Mn;

further, the preparation method of the I-II-V group diluted magnetic semiconductor material with high Curie temperature comprises the following steps:

a. according to the chemical formula Li_1.04(Cd_1-x,Mn_x) The stoichiometric ratio of As is that Li flakes, Cd powder, As powder and Mn powder with the purity of more than or equal to 99.99 percent are mixed under the vacuum degree of water and oxygen concentration of less than 0.01 ppm;

sealing and vacuumizing the monomer mixture;

c. placing the sealed elementary substance mixture in a high-temperature heating furnace, firstly heating to 180-;

further, in step b, the monomer mixture is placed in a quartz tube and pumped 10 by a tube sealing machine^-4Sealing and storing the Tour after high vacuum;

further, in the step c, the heating rate and the cooling rate are both 0.3-0.7 ℃/min;

further, heating to 200 ℃ at a heating rate of 0.5 ℃/min and keeping the temperature for 24 hours, then heating to 540 ℃ at the same heating rate and keeping the temperature for 60 hours, then heating to 680 ℃ at the same heating rate and keeping the temperature for 55-70 hours, finally cooling to 200 ℃ at a cooling rate of 0.5 ℃/min and naturally cooling to room temperature.

The invention has the beneficial effects that: the I-II-V family diluted magnetic semiconductor material with high Curie temperature and the preparation method thereof disclosed by the invention are novel diluted magnetic semiconductors which can be regulated and controlled by charge and spin separation, and the material has excellent magnetoelectric properties and obvious ferromagnetic ordering besides the Curie temperature of 318K. The preparation method of the semiconductor material is simple, and the problem of chemical solid solubility is solved by equivalently doping Mn ions at the Cd ion site; the concentration of the current carrier can be successfully regulated and controlled by adjusting the stoichiometric number of the Li ions, and when the doping concentration is 6 percent, the saturation magnetic moment reaches 3.69 mu_BMn, spontaneous magnetic moment up to 0.32 mu_Band/Mn. The alloy material has the small coercive force of 20-40Oe, the conductivity is weakened along with the increase of the doping concentration, the resistivity is close to 30 omega-cm when the doping concentration is 15%, and due to the properties of a magnetic material and a semiconductor, the alloy material can simultaneously control two degrees of freedom of spin and charge of electrons, has ferromagnetism at room temperature, and has great application prospects in multiple fields such as communication, storage, calculation and the like.

Drawings

The invention is further described below with reference to the following figures and examples:

FIG. 1 shows Li obtained in example one_1.04(Cd_1-x,Mn_x) An X-ray diffraction pattern of As polycrystalline material;

FIG. 2 shows Li obtained in example one_1.04(Cd_1-x,Mn_x) An X-ray diffraction pattern of As polycrystalline material after annealing;

FIG. 3 shows Li obtained in example one_1.04(Cd_1-x,Mn_x) Of polycrystalline As materialAn M-T diagram;

FIG. 4 shows Li obtained in example one_1.04(Cd_1-x,Mn_x) M-H diagram of As polycrystalline material;

FIG. 5 shows Li obtained in example one_1.04(Cd_1-x,Mn_x) rho-T plot of As polycrystalline material;

FIG. 6 is a sample of polycrystalline material and a sample after tableting.

Detailed Description

Example one

The group I-II-V diluted magnetic semiconductor material with high Curie temperature of the embodiment has a chemical formula of Li_1.04(Cd_1-x,Mn_x) As, x is 0.02. The preparation method comprises the following steps:

a. mixing a mixture of four elementary substances of Li blocks, Cd powder, As powder and Mn powder with the purity of more than or equal to 99.99% in a quartz test tube under the vacuum degree of water and oxygen concentration of less than 0.01ppm, wherein the element ratio is Li: cd: as: mn 1.04: 1-x: 1: x. In order to uniformly mix various elements, a Li block can be cut into small slices in a glove box, and then the four elementary substances are put into a quartz test tube according to the proportion, so that the elements are fully and uniformly mixed;

b. pumping the quartz test tube filled with the mixed material to 10 degrees by using a tube sealing machine^-4After the high vacuum of Tour, the package is sealed. Therefore, the condition that a single substance sample is oxidized before crystallization to cause impurity of a sintered polycrystalline sample can be avoided; c. placing the sealed quartz test tube in a high-temperature tube furnace, heating the tube furnace to 200 ℃ at the speed of 0.5 ℃/min and keeping the temperature for 24 hours under normal pressure to form Li-Cd alloy in the quartz tube, heating to 540 ℃ at the speed of 0.5 ℃/min and keeping the temperature for 60 hours, heating to 680 ℃ at the speed of 0.5 ℃/min and keeping the temperature for 65 hours to promote crystallization, and finally cooling to 200 ℃ at the speed of 0.5 ℃/min and naturally cooling to room temperature; the I-II-V family diluted magnetic semiconductor polycrystalline material is prepared.

Example two

The group I-II-V diluted magnetic semiconductor material with high Curie temperature of the embodiment has a chemical formula of Li_1.04(Cd_1-x,Mn_x) As, x is 0.04. The preparation method comprises the following steps:

a. mixing a mixture of four elementary substances of Li blocks, Cd powder, As powder and Mn powder with the purity of more than or equal to 99.99% in a quartz test tube under the vacuum degree of water and oxygen concentration of less than 0.01ppm, wherein the element ratio is Li: cd: as: mn 1.04: 1-x: 1: x. In order to uniformly mix various elements, a Li block can be cut into small slices in a glove box, and then the four elementary substances are put into a quartz test tube according to the proportion, so that the elements are fully and uniformly mixed;

b. pumping the quartz test tube filled with the mixed material to 10 degrees by using a tube sealing machine^-4After the high vacuum of Tour, the package is sealed. Therefore, the condition that a single substance sample is oxidized before crystallization to cause impurity of a sintered polycrystalline sample can be avoided;

c. placing the sealed quartz test tube in a high-temperature tube furnace, heating the tube furnace to 180 ℃ at the speed of 0.3 ℃/min and keeping the temperature for 23 hours under normal pressure, heating to 500 ℃ at the speed of 0.3 ℃/min and keeping the temperature for 58 hours, heating to 650 ℃ at the speed of 0.3 ℃/min and keeping the temperature for 55 hours, cooling to 180 ℃ at the speed of 0.3 ℃/min, and naturally cooling to room temperature; the I-II-V family diluted magnetic semiconductor polycrystalline material is prepared.

EXAMPLE III

The group I-II-V diluted magnetic semiconductor material with high Curie temperature of the embodiment has a chemical formula of Li_1.04(Cd_1-x,Mn_x) As, x is 0.06. The preparation method comprises the following steps:

a. mixing a mixture of four elementary substances of Li blocks, Cd powder, As powder and Mn powder with the purity of more than or equal to 99.99% in a quartz test tube under the vacuum degree of water and oxygen concentration of less than 0.01ppm, wherein the element ratio is Li: cd: as: mn 1.04: 1-x: 1: x. In order to uniformly mix various elements, a Li block can be cut into small slices in a glove box, and then the four elementary substances are put into a quartz test tube according to the proportion, so that the elements are fully and uniformly mixed;

b. pumping the quartz test tube filled with the mixed material to 10 degrees by using a tube sealing machine^-4After the high vacuum of Tour, the package is sealed. Therefore, the condition that a single substance sample is oxidized before crystallization to cause impurity of a sintered polycrystalline sample can be avoided;

c. placing the sealed quartz test tube in a high-temperature tube furnace, heating the tube furnace to 230 ℃ at the speed of 0.7 ℃/min and keeping the temperature for 25 hours under normal pressure, then heating to 600 ℃ at the speed of 0.7 ℃/min and keeping the temperature for 62 hours, then heating to 700 ℃ at the speed of 0.7 ℃/min and keeping the temperature for 70 hours, finally cooling to 230 ℃ at the speed of 0.7 ℃/min and naturally cooling to room temperature; the I-II-V family diluted magnetic semiconductor polycrystalline material is prepared.

Example four

The group I-II-V diluted magnetic semiconductor material with high Curie temperature of the embodiment has a chemical formula of Li_1.04(Cd_1-x,Mn_x) As, x is 0.08. The preparation method comprises the following steps:

a. mixing a mixture of four elementary substances of Li blocks, Cd powder, As powder and Mn powder with the purity of more than or equal to 99.99% in a quartz test tube under the vacuum degree of water and oxygen concentration of less than 0.01ppm, wherein the element ratio is Li: cd: as: mn 1.04: 1-x: 1: x. In order to uniformly mix various elements, a Li block can be cut into small slices in a glove box, and then the four elementary substances are put into a quartz test tube according to the proportion, so that the elements are fully and uniformly mixed;

b. pumping the quartz test tube filled with the mixed material to 10 degrees by using a tube sealing machine^-4After the high vacuum of Tour, the package is sealed. Therefore, the condition that a single substance sample is oxidized before crystallization to cause impurity of a sintered polycrystalline sample can be avoided;

c. placing the sealed quartz test tube in a high-temperature tube furnace, heating the tube furnace to 180 ℃ at the speed of 0.3 ℃/min and keeping the temperature for 25 hours under normal pressure, then heating to 600 ℃ at the speed of 0.3 ℃/min and keeping the temperature for 58 hours, then heating to 650 ℃ at the speed of 0.7 ℃/min and keeping the temperature for 70 hours, finally cooling to 180 ℃ at the speed of 0.3 ℃/min and naturally cooling to room temperature; the I-II-V family diluted magnetic semiconductor polycrystalline material is prepared.

EXAMPLE five

This exampleThe I-II-V group diluted magnetic semiconductor material with high Curie temperature has the chemical formula of Li_1.04(Cd_1-x,Mn_x) As, x is 0.10. The preparation method comprises the following steps:

a. mixing a mixture of four elementary substances of Li blocks, Cd powder, As powder and Mn powder with the purity of more than or equal to 99.99% in a quartz test tube under the vacuum degree of water and oxygen concentration of less than 0.01ppm, wherein the element ratio is Li: cd: as: mn 1.04: 1-x: 1: x. In order to uniformly mix various elements, a Li block can be cut into small slices in a glove box, and then the four elementary substances are put into a quartz test tube according to the proportion, so that the elements are fully and uniformly mixed;

b. pumping the quartz test tube filled with the mixed material to 10 degrees by using a tube sealing machine^-4After the high vacuum of Tour, the package is sealed. Therefore, the condition that a single substance sample is oxidized before crystallization to cause impurity of a sintered polycrystalline sample can be avoided;

c. placing the sealed quartz test tube in a high-temperature tube furnace, heating the tube furnace to 230 ℃ at the speed of 0.7 ℃/min and keeping the temperature for 23 hours under normal pressure, heating to 500 ℃ at the speed of 0.7 ℃/min and keeping the temperature for 62 hours, heating to 700 ℃ at the speed of 0.3 ℃/min and keeping the temperature for 55 hours, cooling to 230 ℃ at the speed of 0.7 ℃/min, and naturally cooling to room temperature; the I-II-V family diluted magnetic semiconductor polycrystalline material is prepared.

EXAMPLE six

The group I-II-V diluted magnetic semiconductor material with high Curie temperature of the embodiment has a chemical formula of Li_1.04(Cd_1-x,Mn_x) As, x is 0.15. The preparation method comprises the following steps:

a. mixing a mixture of four elementary substances of Li blocks, Cd powder, As powder and Mn powder with the purity of more than or equal to 99.99% in a quartz test tube under the vacuum degree of water and oxygen concentration of less than 0.01ppm, wherein the element ratio is Li: cd: as: mn 1.04: 1-x: 1: x. In order to uniformly mix various elements, a Li block can be cut into small slices in a glove box, and then the four elementary substances are put into a quartz test tube according to the proportion, so that the elements are fully and uniformly mixed;

b. pumping the quartz test tube filled with the mixed material to 10 degrees by using a tube sealing machine^-4After the high vacuum of Tour, the package is sealed. Therefore, the condition that a single substance sample is oxidized before crystallization to cause impurity of a sintered polycrystalline sample can be avoided;

c. placing the sealed quartz test tube in a high-temperature tube furnace, heating the tube furnace to 210 ℃ at the speed of 0.6 ℃/min and keeping the temperature for 25 hours under normal pressure, heating to 550 ℃ at the speed of 0.6 ℃/min and keeping the temperature for 60 hours, heating to 680 ℃ at the speed of 0.6 ℃/min and keeping the temperature for 68 hours, cooling to 210 ℃ at the speed of 0.6 ℃/min, and naturally cooling to room temperature; the I-II-V family diluted magnetic semiconductor polycrystalline material is prepared.

Test example: the polycrystalline sample prepared in the first example is fully ground into powder in a mortar, and 10-50mg of the polycrystalline sample is taken for VSM magnetic measurement and XRD structure characterization. Taking the rest powder in proper amount, tabletting with a tabletting machine, placing into a quartz test tube, vacuumizing again, sealing, packaging, and annealing in a tube furnace.

The annealing scheme comprises the following steps: raising the temperature from room temperature to 200 ℃ within 4h, raising the temperature to 400 ℃ within 4h, preserving the heat for 8h, raising the temperature to 600 ℃ within 4h, preserving the heat for 16h, reducing the temperature to 200 ℃ within 4h, and naturally cooling to room temperature. And obtaining the annealed I-II-V family diluted magnetic semiconductor bulk material. The obtained sample was taken out, and silvery white precipitated seeds on the surface of the sample were ground on a sandpaper until the surface was smooth.

The electrical property measurement and XRD structure characterization measurement are carried out by using a VSM instrument, and the results are as follows:

FIG. 1 shows Li obtained_1.04(Cd_1-x,Mn_x) And after analysis by Jade software, peak positions of LiCDAs intrinsic substances and various doped samples correspond to standard cards, which shows that the preparation of the LiCDAs and the polycrystalline materials with different doping concentrations is successful, and the peak positions obviously shift towards the right along with the increase of Mn doping amount As can be seen from the 220 peak positions, which shows that Mn is successfully doped.

FIG. 2 is Li_1.04(Cd_1-x,Mn_x) XRD bulk structure characterization pattern, LiCd, of As polycrystalline sample after tabletting and annealingAs eigen body and each doped sample peak position correspond to the standard card, which shows that the sample structure after annealing is not changed, the sample is still the target sample, and the peak position of 220 is cleaved, and the left cleaved peak is gradually reduced and the right cleaved peak is gradually increased along with the increase of the doping concentration, which shows that Mn is successfully dissolved in solid solution.

FIG. 3 is a graph of LiCDAs intrinsic and M-T at various doping levels. The measurement is to take 10-50mg of a ground polycrystalline powder sample and put the sample into a magnetic measurement capsule, put the sample into VSM, measure a magnetic field of 300Oe, measure two M-T curves of field cooling and zero field cooling, and measure the temperature range of 50-390K. Around 320K, a ferromagnetic phase change can be observed. At lower temperatures, a splitting of the two magnetization curves can be observed, indicating that ferromagnetic ordering has occurred. The temperature at which magnetization suddenly increases is defined as the Curie temperature (T)_c). T at all doping levels_cAre all around 318K. And when the doping concentration is 6%, the spontaneous magnetic moment is 0.32 mu_B/Mn。

FIG. 4 shows M-H plots of LiCDAs precursors and doping levels. The measurement temperature is 50K, all samples show obvious hysteresis regression, and the coercivity is small, about 20-40Oe, and the application of spin operation is facilitated due to the small coercivity. And also at the doping concentration of 6%, the saturation magnetic moment reaches 3.69 mu_B/Mn。

FIG. 5 is a plot of LiCDAs intrinsic and rho-T at each doping level. The measurement needs to place the annealed block material on sand paper for grinding, after the silvery white precipitated crystal seeds and impurities on the surface are ground to be smooth, a four-wire resistance measuring method is used for placing a sample, the sample is placed in VSM, and an ETO module is used for measurement. The temperature range is 50-350K, and the resistivity of the LiCDAs intrinsic body and each doping amount sample is reduced along with the increase of the temperature in the whole temperature range, so that the semiconductor property is obvious. And the resistivity increases with increasing doping concentration, approaching 30 Ω · cm.

FIG. 6 shows a polycrystalline material obtained by a high-temperature solid-phase method on the left and a bulk material obtained by annealing after tabletting on the right.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.