具有磁弹耦合的亚铁磁Mn2Sb基合金磁致应变及各向异性磁电阻研究

Mn2Sb基合金以其特有的亚铁磁/反铁磁相变备受关注。除相变机制外，部分研究也涉及到磁热效应和磁电阻，但合金的磁致应变目前还鲜有报道。研究发现，合金发生磁相变时伴随有大的晶格常数突变，具有强的磁弹耦合，预示着具有大的磁致应变；此外，由于合金天然的层状结构类似于多层膜，磁电阻应该会出现各向异性。因此本项目拟以Mn2Sb基合金为研究对象，探索通过调节成分和利用放电等离子体烧结、微波烧结等烧结方式以及喷铸、热模铸造等定向凝固技术调控磁相变，增强磁弹耦合，增加合金取向度。前期预研结果表明，我们在合适成分的合金中观察到大的磁致应变和各向异性磁电阻效应。我们将对合金磁致应变及各向异性磁电阻的测量、表征及其潜在应用等进行研究。最后通过第一性原理计算合金态密度、带结构、离子占位、元素杂化及层内层间相互作用，为理解合金相变调控机制、磁弹耦合增强机制、各向异性磁电阻机理和拓宽合金实际应用寻找实验和理论支持。

A considerable attention has been paid to the ferrimagnetic Mn2Sb-based alloys due to their peculiar magnetic phase transition between the ferrimagnetic and antimagnetic states. Besides the mechanism of magnetic transition, magnetocaloric and magnetoresistance effect have also been investigated. But almost no magnetostriction of Mn2Sb-based alloys are noticed by far. It is reported that the sudden change of lattice parameters will be accompanied when the magnetic transition happens in the ferrimagnetic Mn2Sb-based alloys, which indicates the large magnetoelastic, and in turn suggests the large magnetostriction. In addition, owing to the natural layer structure, which is similar to the multilayer film, the magnetoresistance of Mn2Sb-based alloys should show the anisotropy. Therefore, the ferrimagnetic Mn2Sb-based slloys with the appropriate composition will be chosen as the investigated subject of this project. We intend to control the magnetic transition, enhance the magnetoelastic coupling, and make the alloys form the better texture by regulating the composition and adopting many sintering methods such as spark plasma sintering and microwave sintering, and directional solidification techniques including spray casting and hot-mold casting. Our previous research results indicate that the the large magnetostriction and anisotropic magnetoresistance has been observed in the ferrimagnetic Mn2Sb-based slloys with the appropriate composition. We will study the measurement, the representation, and potential application of the magnetostriction and anisotropic magnetoresistance. Finally, the first-principles calculations about the density of state, band structure, metallic ion sites, element hybridization, and the inter- or intra- interaction in Mn2Sb-based alloys will be carried out. By these calculations, we try to search for the exprimental and theoretical support for the physical mechanics about the regulation of the magnetic phase transition, the enhancement of magnetoelastic coupling, and the anisotropic magnetoresistance in Mn2Sb-based alloys, broadening their the practical application.