Weyl fermion-based spin current generation (WeylSPIN)

由于它们的拓扑保护，螺旋自旋织构，外尔半金属是很有前途的电驱动自旋发电机。本项目的目的是获得一个基本的理解的自旋电流和自旋动力学在多和单层的两个II型Weyl半金属WTe2和MoTe2。为了实现这一任务，我们计划结合联合收割机磁输运光谱实验，它可以产生的自旋极化，与时间和空间分辨的螺旋光电流和电导测量，它可以提供自旋弛豫时间。通过获得这两个，自旋极化和弛豫时间为一个和相同的样品在两个组中研究，我们设想确定相关的“光电”时间和潜在的散射机制的晶体方向相关的自旋和电荷输运过程中的dielectric片。进一步的目标是确定个体的贡献的体和表面状态的自旋电流的产生，以及澄清详细的两种可能的晶相和单层的数量的影响。对于后期的项目阶段，我们打算证明一个贝里曲率为基础的开关的自旋电流产生的静电门场，沿着与评估相应的运输时间尺度和签名。

Owing to their topologically protected, helical spin texture, Weyl semimetals are promising as electrically driven spin generators. The present project aims at gaining a fundamental understanding of the spin currents and spin dynamics in multi- and monolayers of the two type-II Weyl semimetals WTe2 and MoTe2. To reach this task, we plan to combine magnetic transport spectroscopy experiments, which can yield the spin polarisation, with time- and spatially-resolved helical photocurrent and -conductance measurements, which can provide the spin relaxation times. By gaining access to both, spin polarisation and relaxation times for one-and-the-same samples studied in the two groups, we envision determining the relevant “optoelectronic” times and underlying scattering mechanisms for the crystallographic direction-dependent spin and charge transport processes in the ultrathin sheets. Further objectives are to identify the individual contributions of the bulk and surface states to the spin current generation, as well as to clarify in detail the influence of the two possible crystal phases and the number of monolayers. For the later project stage, we intend demonstrating a Berry curvature-based switching of the spin current generation by an electrostatic gate field, along with evaluating the corresponding transport time scales and signatures.