Development of a spin-polarized scanning tunneling potentiometry system and its application to micro fabricated surface Rashba systems

本项目的目的是在表面Rashba系统上进行扫描隧道电位(STP)测量，并探索其电荷/自旋输运现象的有趣性质。为此，我们新建了一台扫描隧道显微镜(STM)，并研制了自己的STP测量系统。我们已经证明，当施加电流通过表面时，可以同时用STM绘制表面形貌图，同时用STP绘制电位分布。利用在Si(111)衬底上生长的超薄Bi膜，我们证明可以正确地测量电势梯度。此外，我们还发现了一种利用超薄Bi2Se_3薄膜进行非局域输运测量来实现表面态原位微加工和自旋霍尔效应测量的方法。

The purpose of the present project is to perform scanning tunneling potentiometry (STP) measurements on surface Rashba systems and explore the intriguing nature of its charge/spin transport phenomena. Therefore we have newly constructed a scanning tunneling microscope (STM) and furthermore, made our own measurement system for STP measurements. We have shown that it is possible to simultaneously map the surface topography with STM while mapping the potential distribution with STP when applying electrical current through the surface. Using ultrathin Bi films formed on Si(111) substrates, we have shown that the potential gradient can be measured properly. We have additionally found a way to micro fabricate surface states in situ and measure the spin Hall effect using nonlocal transport measurements using ultrathin Bi2Se3 films.