Weyl半金属二维晶体材料在光、磁场下的电输运性能研究

Weyl semi-metals have many novel physical properties including high carrier concentration, giant magnetoresistance effect, chiral electric response on magnetic field, quantum spin Hall effect, and exotic quantum oscillation of magnetoresistance due to their topological electronic structures, which is the good candidate materials to build the small and low dissipation electronics. In this project, the Weyl semi-metallic 2D materials with few layers and single layer will be prepared by Liquid-Exfoliating the single crystal. The electronic and geometry structures and phonon modes will be characterized by ARPES, aberration corrected transmission electron microscope, and polarized Raman spectra. The spin-dependent and quantum-related transport properties will be investigated under low temperature, strong magnetic field, and optic field to reveal the relationship between their structures and the basic carries concentration and mobility to reveal the mechanism of the charge, spin polarization carrier, valley polarization carrier, and transport behavior of other quasiparticles. Combinated with the 1D and 2D time-resolved ultrafast spectroscopy and first principles calculation, the physical mechanism of electron structures, carrier transport, spin-orbit coupling, photoelectric properties, and band change.

Weyl半金属二维晶体材料因具有拓扑电子结构而表现出高载流子浓度、庞大磁阻现象、对磁场具有手性的电响应、量子自旋霍尔效应、磁阻的奇特量子振荡等多种新颖的物理性能，成为构建小尺寸、极低能耗电子器件的良好候选材料。本项目拟采用液相超声剥离Weyl半金属单晶而制备出少层和单层Weyl半金属二维晶体材料，通过角分辨光电子能谱（ARPES）、球差校正透射电镜、极化Raman光谱等研究其与层数相关的电子、几何结构和声子振动模式，系统研究其在低温、强磁场、光场作用条件下的磁电阻效应、各向异性输运、霍尔效应、磁阻量子振荡等自旋和量子输运性能，获得其中的电荷、自旋极化载流子、谷极化载流子、其它准粒子的输运行为，揭示其结构和基本载流子的浓度、迁移率等输运特性间的关联。结合一维和二维时间分辨超快光谱技术和第一性原理计算，揭示其电子结构、载流子输运、自旋轨道耦合、光电特性、超快响应及能带变化的物理机制。

Weyl半金属二维晶体材料因具有拓扑电子结构而表现出高载流子浓度、庞大磁阻现象、对磁场具有手性的电响应、量子自旋霍尔效应、磁阻的奇特量子振荡等多种新颖的物理性能，成为构建小尺寸、极低能耗电子器件的良好候选材料。本项目采用自助熔剂和化学气相传输方法制备了三种Weyl半金属Co3Sn2S2、WTe2和MoTe2的高质量单晶材料，利用化学气相沉积法制备了少层和单层的WTe2和MoTe2两种Weyl半金属二维晶体材料，采用液相超声剥离法大规模制备出WSe2少层二维晶体材料。通过球差校正透射电镜、Raman光谱等研究了这些材料与层数相关的电子、几何结构和声子振动模式，系统研究了其在低温、强磁场、光场作用条件下的磁电阻效应、各向异性输运、霍尔效应、磁阻量子振荡等自旋和量子输运性能，获得了其中的电荷、自旋极化载流子、谷极化载流子、其它准粒子的输运行为，揭示了其结构和基本载流子的浓度、迁移率等输运特性间的关联。结合极低温强磁场扫描隧道显微镜和第一性原理计算，揭示了其电子结构、载流子输运、自旋轨道耦合、光电特性及能带变化的物理机制。