论文标题
单层半导体中长电子自旋传输长度的光学检测
Optical detection of long electron spin transport lengths in a monolayer semiconductor
论文作者
论文摘要
使用空间分辨的光泵探针实验，我们测量了单个WSE2单层中很长的距离（数十微米）的自旋/谷极化电子的横向运输。通过将2D电子的费米海局部泵送到高度的自旋/山谷极化（最高75％），使用圆形光线，可以通过空间分离和线性启动的探测激光剂引起的电子极化的横向扩散。在高达20微米的泵探针分离处观察到高达25％的自旋谷极化。在低温下显示出18 +/- 3 UM的特征自旋/谷扩散长度。对温度，泵的螺旋，泵的强度和电子密度的依赖性突出了旋转松弛时间和泵浦效率在具有旋转 - 瓦利锁定的单层半导体中发挥的关键作用。
Using a spatially-resolved optical pump-probe experiment, we measure the lateral transport of spin/valley polarized electrons over very long distances (tens of micrometers) in a single WSe2 monolayer. By locally pumping the Fermi sea of 2D electrons to a high degree of spin/valley polarization (up to 75%) using circularly-polarized light, the lateral diffusion of the electron polarization can be mapped out via the photoluminescence induced by a spatially-separated and linearly-polarized probe laser. Up to 25% spin-valley polarization is observed at pump-probe separations up to 20 microns. Characteristic spin/valley diffusion lengths of 18 +/- 3 um are revealed at low temperatures. The dependence on temperature, pump helicity, pump intensity, and electron density highlight the key roles played by spin relaxation time and pumping efficiency on polarized electron transport in monolayer semiconductors possessing spin-valley locking.
