Lv Yang-Yang, Zhang Bin-Bin, Li Xiao, Pang Bin, Zhang Fan, Lin Da-Jun, Zhou Jian, Yao Shu-Hua, Chen Y B, Zhang Shan-Tao, Lu Minghui, Liu Zhongkai, Chen Yulin, Chen Yan-Feng
National Laboratory of Solid State Microstructures and Department of Materials Science and Engineering, Nanjing University, Nanjing 210093, China.
National Laboratory of Solid State Microstructure and Department of Physics, Nanjing University, Nanjing 210093, China.
Sci Rep. 2016 May 27;6:26903. doi: 10.1038/srep26903.
Recently, the layered semimetal WTe2 has attracted renewed interest owing to the observation of a non-saturating and giant positive magnetoresistance (~10(5)%), which can be useful for magnetic memory and spintronic devices. However, the underlying mechanisms of the giant magnetoresistance are still under hot debate. Herein, we grew the stoichiometric and non-stoichiometric WTe2 crystals to test the robustness of giant magnetoresistance. The stoichiometric WTe2 crystals have magnetoresistance as large as 3100% at 2 K and 9-Tesla magnetic field. However, only 71% and 13% magnetoresistance in the most non-stoichiometry (WTe1.80) and the highest Mo isovalent substitution samples (W0.7Mo0.3Te2) are observed, respectively. Analysis of the magnetic-field dependent magnetoresistance of non-stoichiometric WTe2 crystals substantiates that both the large electron-hole concentration asymmetry and decreased carrier mobility, induced by non-stoichiometry, synergistically lead to the decreased magnetoresistance. This work sheds more light on the origin of giant magnetoresistance observed in WTe2.
最近，层状半金属WTe₂由于被观测到具有非饱和且巨大的正磁阻（~10⁵%）而重新引起了人们的兴趣，这对于磁存储器和自旋电子器件可能是有用的。然而，巨大磁阻的潜在机制仍在激烈争论中。在此，我们生长了化学计量比和非化学计量比的WTe₂晶体，以测试巨大磁阻的稳健性。化学计量比的WTe₂晶体在2 K和9特斯拉磁场下具有高达3100%的磁阻。然而，在最非化学计量比（WTe₁.₈₀）和最高Mo等价替代样品（W₀.₇Mo₀.₃Te₂）中分别仅观测到71%和13%的磁阻。对非化学计量比WTe₂晶体的磁场依赖磁阻分析证实，由非化学计量比引起的大电子 - 空穴浓度不对称性和载流子迁移率降低共同导致了磁阻降低。这项工作为在WTe₂中观测到的巨大磁阻的起源提供了更多线索。
