δ-(Zn,Cr)S(111)表面上的Dzyaloshinsky-Moriya作用:第一性原理计算  

Dzyaloshinsky-Moriya interaction in δ-(Zn, Cr)S(111)surface: First principle calculations

作　　者：李小影 黄灿 朱岩[1] 李晋斌[1] 樊济宇[1] 潘燕飞[1] 施大宁[1] 马春兰 Li Xiao-Ying;Huang Can;Zhu Yan;Li Jin-Bin;Fan Ji-Yu;Pan Yan-Fei;Shi Da-Ning;Ma Chun-Lan(College of Science, Nanjing University of Aeronautics and Astronautics, Najing 210006, China;School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009, China)

机构地区：[1]南京航空航天大学理学院物理系,南京210006 [2]苏州科技大学数理学院物理科学与技术系,苏州215009

出　　处：《物理学报》2018年第13期123-131,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11204131;11374159);江苏省高等学校自然科学研究重大项目(批准号:17KJA140001);江苏省"六大人才高峰"高层次人才项目(批准号:XCL-078)资助的课题~~

摘　　要：根据密度泛函理论的第一性原理计算了具有非中心反演对称的异质结δ-(Zn,Cr)S(111)体系的原子结构和电子结构.Cr原子之间通过第一层S原子传递磁性相互作用.结合广义布洛赫条件,又进一步计算了反方向的自旋螺旋能量与波矢的色散关系E(q)与E(-q).E(q)与E(-q)能量之差反映了δ-(Zn,Cr)S(111)的S层与Cr层之间空间反演对称性破缺引起的DMI的大小.通过海森伯相互作用(HBI)模型与Dzyaloshinsky-Moriya作用(DMI)模型拟合第一性原理计算值,得到了Cr原子间各近邻的HBI参数J_1-J_4与DMI参数d-_1,d_2.在δ-(Zn,Cr)S(111)中,Cr原子间的耦合为M型反铁磁.DMI参数d_1为-0.53 meV,为顺时针手性DMI,在δ-(Zn,Cr)S(111)界面上有可能会产生斯格明子.本文计算表明,磁性和非磁性半导体界面有可能存在DMI,为理论研究和磁存储技术的进步开拓一个新的方向.According to density functional theory calculations, we elucidate the atomic and electronic structure of δ-（Zn,Cr）S（111） surface. The magnetic interaction between Cr atoms is via S atoms close to the Cr layer. This interaction is shown by the analysis of spin charge contour plot and partial density of states（DOS） of each atom. The DOSs of other S atoms are non magnetic and have no magnetic exchange with the Cr layer. E（q） and E（-q） are the dispersions between energy E and wave vector q of spin spiral in the opposite directions. They are calculated with generalized Bloch equations and all the magnetic moments of Cr atoms are arranged in the plane perpendicular to the δ-（Zn, Cr）S（111）film. The differences between E（q） and E（-q） are caused by the interface of δ-（Zn, Cr）S（111）, where the symmetry of space perpendicular to the film is broken. Effective Heisenberg exchange interaction（HBI） and Dzyaloshinsky-Moriya interaction（DMI） parameters between different neighbors（J_i and d_i） are derived by well fitting the ab initio spin spiral dispersion E（q） to HBI with DMI model and E（q）-E（-q） to DMI model, respectively. The J_2 plays a major role with a large negative value of -9.04 me V. The J_1 is about 2/5 of J_2, and J_3 is about 1/4 of J_2 with positive value. The DMI d_1 is-0.53 meV, and d_2 is 0.07 meV. With these HBI parameters, E（0） is the largest one at which δ-（Zn, Cr）S（111） has no ferromagnetic interface. The E（q） has its lowest energy with the q at M = b_1/2 in the first Brillouin zone. Hence, δ-（Zn,Cr）S（111） is an M-type antiferromagnetic（AFM） material. In this type of AFM configuration, magnetic moments of Cr atom in a line along b_2 are parallel to each other, and antiparallel to the magnetic moments in adjacent lines. The E（q） at K = b_1/2 ＋ b_2/2 is almost as large as that at Γ point. The value of DMI parameter d_1 is about 1/5 of that on Co/Pt3 interface and 1/2 of Co/graphene. However, it is a negat

关 键 词：第一性原理 Dzyaloshinsky-Moriya相互作用 异质结 斯格明子 

分 类 号：O469[理学—凝聚态物理]