反铁磁CrS_(2)到铁磁MoSe_(2)/CrS_(2)磁性转变研究

Magnetic transition from antiferromagnetic CrS_(2)to ferromagnetic MoSe_(2)/CrS

通过第一性原理研究了二维单层CrS_(2)与双层CrS_(2)/MoSe_(2)体系的原子结构和磁性结构.利用广义布洛赫条件计算了自旋螺旋的能量与自旋螺旋波矢之间的色散关系E(q),并通过海森堡模型拟合该曲线,分别得到了单层CrS_(2)体系和CrS_(2)/MoSe_(2)双层体系的多近邻海森堡作用(HBI)参数J1–J6.然后通过拟合得到的HBI参数作出全布里渊区的E(q).研究发现,非磁性单层MoSe_(2)与单层CrS_(2)形成异质结后改变了单层CrS_(2)的磁性结构,使其从层内反铁磁排布转变成层内铁磁排布.MoSe_(2)层使得Cr原子的态密度更延展,并且CrS_(2)/MoSe_(2)中电子气从金属性的CrS_(2)转移到半导体的MoSe_(2)中,这导致CrS_(2)中反铁磁作用的RKKY相互作用的减小,最终使得CrS_(2)/MoSe_(2)呈现铁磁性.本文为更好地探索二维磁性材料的各种相互作用机制,如双交换、超交换和RKKY交换,设计、寻找高居里温度磁性材料和分析各种二维磁性体系奠定了一定的基础.

We studied the atomic and magnetic structures of the two-dimensional(2 D) single-layer CrS_(2)and double-layer MoSe_(2)/CrS_(2)systems based on the first principles. In this paper, the generalized Bloch condition was used to calculate the dispersion relationship E(q) between the energy of the spin spiral and spin spiral wave vector q. The curve was fitted by the Heisenberg model, and the multiple nearest neighbor Heisenberg interaction(HBI) parameters J1–J6 of the singlelayer CrS_(2)and MoSe_(2)/CrS_(2)double-layer systems were obtained. The fitted HBI parameters were used to derive the E(q)over the full Brillouin zone. The paper found that the nonmagnetic MoSe_(2)layer changes the magnetic structure of CrS_(2)from an intralayer antiferromagnetic arrangement to an intralayer ferromagnetic arrangement. The mechanism can be summarized as follows: the MoSe_(2)layer expands the density of states of the Cr atoms, and the electron gas in MoSe_(2)/CrS_(2)is transferred from the metallic CrS_(2)to the semiconductor MoSe_(2), resulting in a reduction in the Ruderman-KittelKasuya-Yosida(RKKY) interaction of the antiferromagnetic effect in CrS_(2). Finally, MoSe_(2)/CrS_(2)exhibits ferromagnetism. This article lays the foundation to explore the various interaction mechanisms of 2 D magnetic materials, such as double exchange and RKKY exchange, for the design and search for high-Curie-temperature magnetic materials and analysis of various 2 D magnetic systems.