CN-121974689-A - Magnetic double perovskite Sr2FeMoO6Low-field magnetic resistance regulating and controlling method and application of ceramic

Abstract

The invention discloses a low-field magnetic resistance regulating and controlling method and application of magnetic double perovskite Sr 2 FeMoO 6 ceramic, and the influence mechanism of Fe/Mo dislocation defect (ASD) and grain boundary strength in Sr 2 FeMoO 6 (SFMO) ceramic on low-field magnetic resistance (LFMR) can be effectively regulated and controlled by simply regulating the cooling rate. As the rate of decrease increases, the ASD concentration in the obtained SFMO samples appears to increase monotonically, with a corresponding decrease in saturation magnetization. The grain boundary strength is obviously increased, the macroscopic appearance is that the resistivity is increased by 1-3 orders of magnitude, the grain boundary tunneling barrier is obviously enhanced, the performance of LFMR is obviously improved despite the increase of Fe/Mo ASD, and the grain boundary effect master control LFMR is illustrated. The invention can realize effective regulation and control of the functional characteristics of the double perovskite ceramic by regulating the cooling rate, and provides a practical technical path free from component modification for optimizing the material performance.

Inventors

• WANG JINFENG
• ZHANG YANMING
• GU YADONG
• FENG XIAOBO
• NI YU
• ZANG YONGJIAN
• Jiang guanhu

Assignees

• 云南师范大学

Dates

Publication Date

20260505

Application Date

20260204

Claims (8)

1. 1. The low-field magnetic resistance regulation and control method of the magnetic double perovskite Sr 2 FeMoO 6 ceramic is characterized by comprising the following specific steps of: Step S1, respectively weighing raw materials SrCO 3 powder, fe 2 O 3 powder and MoO 3 powder according to the stoichiometric ratio of a target product chemical formula Sr 2 FeMoO 6 , placing the raw materials in an agate tank, adding alcohol, and performing ball milling treatment to uniformly mix the raw materials to obtain mixed slurry; s2, drying the mixed slurry obtained in the step S1, grinding and uniformly mixing the mixed slurry by an agate mortar, and presintering the mixed material in an air atmosphere at 800-1000 ℃ for 8-12 hours to obtain a powder mixture; Step S3, adding alcohol into the powder mixture obtained in the step S2 for secondary ball milling and mixing treatment, drying, and pressing the obtained powder into round slices with the diameter of 10mm plus or minus 1mm and the thickness of 1mm plus or minus 0.1mm by using the pressure of 2-5 MPa; And S4, placing the round sheet obtained in the step S3 in a tube furnace, introducing flowing mixed protective gas with the volume fraction of 5% H 2 /95% Ar, preserving heat for 8-12 hours at 1100-1300 ℃, setting different cooling rates, cooling to room temperature, regulating the low-field magnetic resistance effect in the double perovskite Sr 2 FeMoO 6 ceramic by adjusting the cooling rates, wherein the cooling rates are 5-20 ℃/min, the Fe/Mo dislocation defect content in the crystal lattice of the double perovskite Sr 2 FeMoO 6 ceramic is gradually increased by 9-17% along with the increase of the cooling rates, the grain boundary strength is obviously increased by 1-3 orders of magnitude, and the low-field magnetic resistance performance of the double perovskite Sr 2 FeMoO 6 ceramic is obviously improved.
2. 2. The method for regulating and controlling low-field magnetic resistance of the magnetic double perovskite Sr 2 FeMoO 6 ceramic according to claim 1, wherein the cooling rate in the step S4 is preferably 20 ℃ per minute, the pure-phase double perovskite Sr 2 FeMoO 6 ceramic is finally prepared under the condition that the content of Fe/Mo inversion defects in crystal lattices is 17%, the resistivity is the highest, and the low-field magnetic resistance performance is the best and is up to-37% (10K and 1T).
3. 3. The low-field magnetic resistance regulating method of the magnetic double perovskite Sr 2 FeMoO 6 ceramic according to claim 1, wherein the diffraction peak of the double perovskite Sr 2 FeMoO 6 ceramic obtained in the step S4 is completely matched with the double perovskite structure characteristics of tetragonal system (space group I4/m), other hetero-phase diffraction peaks are not seen, the intensity of the (101) superlattice diffraction peak corresponding to 19.8 degrees is monotonically decreased along with the increase of the cooling rate, and the ordering degree of Fe/Mo is obviously inhibited under the condition of quick cooling.
4. 4. The low-field magnetic resistance regulating method of the magnetic double perovskite Sr 2 FeMoO 6 ceramic according to claim 1, wherein the double perovskite Sr 2 FeMoO 6 ceramic obtained in the step S4 has soft ferromagnetic property, and the saturated magnetic moment Ms is monotonically decreasing along with the increase of the cooling rate.
5. 5. The low-field magnetic resistance regulation and control method of the magnetic double perovskite Sr 2 FeMoO 6 ceramic according to claim 1 is characterized in that in the step S4, along with the increase of the cooling rate, the resistivity of the prepared double perovskite Sr 2 FeMoO 6 ceramic is obviously increased, and the prepared double perovskite Sr 2 FeMoO 6 ceramic shows insulator-like behavior at low temperature, and the carrier transport is inhibited due to the enhancement of the disorder degree of grain boundaries.
6. 6. The method for regulating and controlling low-field magnetic resistance of the magnetic double perovskite Sr 2 FeMoO 6 ceramic according to claim 1, wherein in the step S4, as the cooling rate is increased, the content of Fe/Mo dislocation defects is increased, the low-field magnetic resistance is obviously enhanced at a low temperature, the variation trend of the low-field magnetic resistance is consistent with the variation of the insulating strength of a grain boundary, and the grain boundary condition can be optimized by increasing the cooling rate.
7. 7. The method according to claim 1, wherein the purity of SrCO 3 powder in the step S1 is higher than 99.99%, the purity of Fe 2 O 3 powder is higher than 99.99%, and the purity of MoO 3 powder is higher than 99.99%.
8. 8. Application of the magnetic double perovskite Sr 2 FeMoO 6 ceramic prepared based on the method as claimed in any one of claims 1-7 in high-sensitivity magnetic sensors and detection devices, nonvolatile magnetic memories, spintronics devices or intelligent electromagnetic regulation and stealth devices.

Description

Low-field magnetic resistance regulation and control method and application of magnetic double perovskite Sr 2FeMoO6 ceramic Technical Field The invention belongs to the technical field of magnetoelectric functional materials, and particularly relates to a low-field magnetic resistance regulation and control method and application of magnetic double perovskite Sr 2FeMoO6 ceramic. Background Low field magnetoresistance is a physical effect of a significant change in the resistance of a material under an externally applied weak magnetic field (typically less than one tesla), and sensors, detectors, magnetic memories, and other magneto-electric devices based on this effect have high sensitivity, low power consumption, and miniaturized characteristics. At present, most of the magnetic resistance materials are anisotropic magnetic resistance and giant magnetic resistance multilayer film materials, the main defects of the materials in the former family are that the magnetic resistance effect is generally low (generally less than 5%), which limits the application of the materials in the field of detection requiring high sensitivity, while the giant magnetic resistance multilayer film depends on precise nano-scale artificial heterojunction epitaxial growth, the performance of the giant magnetic resistance multilayer film is extremely sensitive to interface defects and thermal disturbance, the preparation process is complex, the cost is high, and the long-term working stability faces challenges. Aiming at the technical problems existing at present, the exploration of a material system with excellent low-field magnetic resistance and high stability is a key point for pushing the magnetic sensing and storage technology to break through the performance bottleneck and realizing higher sensitivity, lower power consumption and better integration level. Magnetic double perovskite oxides (of the general chemical formula a 2B'B''O6, where a is an alkaline earth or rare earth ion and B'/b″ is a transition metal ion) have been of great interest for their unique structure and magneto-electric properties and potential application in magnetic storage. Compared with the conventional magnetic resistance material (such as an anisotropic magnetic resistance or giant magnetic resistance multilayer film), the low-field magnetic resistance core of the magnetic double perovskite material has the advantages that (1) the high Curie temperature and the superior magnetic resistance effect reduce the dependence of a material system on temperature control and strong fields, (2) electrons and magnetism come from a single chemically adjustable intrinsic crystal structure, no complex artificial multilayer film interface is needed to be relied on, the integration and performance stability of the device are facilitated, and (3) the sensitivity, the power consumption and the thermal stability can be synergistically optimized in a single material by flexibly regulating the type and the order degree of B '/B' position ions. As one of representative materials of A 2B'B''O6 double perovskite oxide, the semi-metal material Sr 2FeMoO6 (SFMO) has the characteristics of higher Curie temperature (Tc-415K), excellent room temperature low field magnetic resistance, 100% spin polarization rate and the like, and the three characteristics of the three materials provide a new opportunity for solving the problems. Regarding the problem of low field magnetoresistance origin in SFMO, it is widely believed that low field magnetoresistance is mainly due to tunneling effects at the magnetic domain boundaries and grain boundaries, corresponding to Fe/Mo dislocation defect (ASD) effects and grain boundary effects, respectively. At present, the two key factors are regulated and controlled by adopting traditional modes such as A/B bit element replacement and second phase modification grain boundary insulating strength, so as to regulate and control low-field magnetic resistance. These conventional methods are complicated in process and introduce a hetero-phase, and the low-field magnetoresistance effect is still not ideal, and further optimization is required. It is therefore important to find a simple and effective experimental process that can significantly optimize the low-field magnetoresistance effect in SFMO. Disclosure of Invention The invention aims at solving the technical problems that the low-field magnetic resistance of the magnetic double perovskite SFMO ceramic is still not ideal and the current regulation and control technology is complex, and provides a simple and effective low-field magnetic resistance regulation and control method of the magnetic double perovskite Sr 2FeMoO6 ceramic, which provides an experimental foundation for the potential application of the materials in the field of wide-temperature-area magnetoelectric devices. The invention adopts the following technical scheme that the low-field magnetic resistance regulation and control method of t