层状过渡金属化合物Fe_3GeTe_2的电子结构和磁学性质研究

Study on the Electronic Structure and Magnetic Properties of Layered Transition Metal Compounds Fe_3GeTe_2

运用第一性原理计算方法,系统研究了层状过渡金属化合物Fe_3GeTe_2的电子结构、磁各向异性能(MAE)、磁交换相互作用和磁转变温度.研究表明PBE密度泛函给出了和实验接近的晶格参数,计算了不同层数化合物的MAE,发现层数对MAE影响不大,其中单层的MAE达到1158μeV,高于常见的铁磁体.另外,还结合伊辛(ISING)模型计算了磁交换相互作用,并通过平均场近似估计材料的居里温度.平衡状态时,居里温度T_c为246K,跟实验值较好地相符.研究磁交换作用和居里温度随应变的变化,计算结果显示,在应力作用下,J_⊥随着应力增大而减小,J_∥则正好相反,导致居里温度在非常大的应力范围内基本保持不变.研究表明单层的Fe_3GeTe_2磁性相当稳定,可作为潜在的自旋电子学材料.

The electronic structure, magnetic anisotropy, magnetic exchange interaction and magnetic transition temperature of layered transition metal compound Fe3GeTe2 are systematically studied by u- sing the first-principle calculation method. It is found that PBE gives lattice parameters which is close to the experiment. The MAE in different layers of compounds is also calculated, and it is found that the number of layers has little effect on the MAE, in which the MAE in single layer is 1158μeV higher than that of the common ferromagnet. In addition, the magnetic exchange interaction with the ISING model is calculated, and the Curie temperature of the material is estimated by the average field approximation. When the balance is in place, the Tc is 246K, which is in good agreement with the experimental value. Apart from that, effects of magnetic exchange and Curie temperature on strain are studied. The results show that, under stress, J∥decreases with increasing stress, J⊥is the opposite, leading to Curie temperature in the very large stress range remains essentially unchanged. It is shown that the magnetic properties of the monolayer Fe3GeTe2 are fairly stable and can be used as potential spin electron.