Scanning Tunneling Microscopy Detection of Surface Spin-Polarized Electron Accumulations in Topological Insulators

Spin-momentum locking in the surface mode of topological insulators leads to the surface accumulations of spin-polarized electrons caused by bias currents through topological insulator samples. It is demonstrated in this letter that surface spin-polarized electron accumulations caused by the above bias currents can be sensed by using scanning tunneling microscopy. The experimental results of this sensing are presented for tin-doped bismuth selenide samples by employing iron-coated tungsten tips as well as nonmagnetic tungsten tips. A linear increase in the spin accumulation as a function of bias current through topological insulator samples is observed.