Jo Na Hyun, Wang Lin-Lin, Orth Peter P, Bud'ko Sergey L, Canfield Paul C
Ames Laboratory Division of Materials Sciences and Engineering, Ames Laboratory, Ames, IA 50011;
Department of Physics and Astronomy, Iowa State University, Ames, IA 50011.
Proc Natl Acad Sci U S A. 2019 Dec 17;116(51):25524-25529. doi: 10.1073/pnas.1910695116. Epub 2019 Dec 2.
Strain describes the deformation of a material as a result of applied stress. It has been widely employed to probe transport properties of materials, ranging from semiconductors to correlated materials. In order to understand, and eventually control, transport behavior under strain, it is important to quantify the effects of strain on the electronic bandstructure, carrier density, and mobility. Here, we demonstrate that much information can be obtained by exploring magnetoelastoresistance (MER), which refers to magnetic field-driven changes of the elastoresistance. We use this powerful approach to study the combined effect of strain and magnetic fields on the semimetallic transition metal dichalcogenide [Formula: see text] We discover that WTe shows a large and temperature-nonmonotonic elastoresistance, driven by uniaxial stress, that can be tuned by magnetic field. Using first-principle and analytical low-energy model calculations, we provide a semiquantitative understanding of our experimental observations. We show that in [Formula: see text], the strain-induced change of the carrier density dominates the observed elastoresistance. In addition, the change of the mobilities can be directly accessed by using MER. Our analysis also reveals the importance of a heavy-hole band near the Fermi level on the elastoresistance at intermediate temperatures. Systematic understanding of strain effects in single crystals of correlated materials is important for future applications, such as strain tuning of bulk phases and fabrication of devices controlled by strain.
应变描述了材料在施加应力时的形变。它已被广泛用于探究从半导体到关联材料等各种材料的输运性质。为了理解并最终控制应变下的输运行为，量化应变对电子能带结构、载流子密度和迁移率的影响至关重要。在此，我们证明通过探索磁致弹性电阻（MER）可以获得大量信息，磁致弹性电阻指的是磁场驱动的弹性电阻变化。我们使用这种强大的方法来研究应变和磁场对半金属过渡金属二硫属化物[化学式：见原文]的综合影响。我们发现WTe在单轴应力驱动下表现出大的且随温度非单调变化的弹性电阻，其可由磁场调节。通过第一性原理和解析低能模型计算，我们对实验观测结果给出了半定量的理解。我们表明在[化学式：见原文]中，载流子密度的应变诱导变化主导了观测到的弹性电阻。此外，迁移率的变化可通过磁致弹性电阻直接获取。我们的分析还揭示了费米能级附近重空穴带在中间温度下对弹性电阻的重要性。系统理解关联材料单晶中的应变效应对于未来的应用很重要，例如体相的应变调控以及应变控制器件的制造。
