Yang Junjie, Colen Jonathan, Liu Jun, Nguyen Manh Cuong, Chern Gia-Wei, Louca Despina
Department of Physics, University of Virginia, Charlottesville, VA 22904, USA.
Ames Laboratory, U.S. Department of Energy, Iowa State University, Ames, IA 50011, USA.
Sci Adv. 2017 Dec 15;3(12):eaao4949. doi: 10.1126/sciadv.aao4949. eCollection 2017 Dec.
Quasi-two-dimensional transition metal dichalcogenides exhibit dramatic properties that may transform electronic and photonic devices. We report on how the anomalously large magnetoresistance (MR) observed under high magnetic field in MoTe, a type II Weyl semimetal, can be reversibly controlled under tensile strain. The MR is enhanced by as much as ~30% at low temperatures and high magnetic fields when uniaxial strain is applied along the crystallographic direction and reduced by about the same amount when strain is applied along the direction. We show that the large in-plane electric anisotropy is coupled with the structural transition from the 1T' monoclinic to the T orthorhombic Weyl phase. A shift of the T-1T' phase boundary is achieved by minimal tensile strain. The sensitivity of the MR to tensile strain suggests the possibility of a nontrivial spin-orbital texture of the electron and hole pockets in the vicinity of Weyl points. Our ab initio calculations show a significant orbital mixing on the Fermi surface, which is modified by the tensile strains.
准二维过渡金属二硫属化物展现出的显著特性可能会改变电子和光子器件。我们报告了在II型外尔半金属MoTe中，在高磁场下观测到的异常大磁电阻（MR）如何在拉伸应变下被可逆控制。当沿晶体学方向施加单轴应变时，在低温和高磁场下MR增强高达约30%，而当沿方向施加应变时，MR降低约相同的量。我们表明，大的面内电各向异性与从1T'单斜相到T正交外尔相的结构转变相关联。通过最小的拉伸应变实现了T - 1T'相界的移动。MR对拉伸应变的敏感性表明在外尔点附近电子和空穴口袋存在非平凡的自旋 - 轨道纹理的可能性。我们的第一性原理计算表明在费米面上存在显著的轨道混合，其会被拉伸应变所改变。
