Observation of spin-dependent tunneling current using optically pumped GaAs microtip

Abstract

The spin-polarized scanning tunneling microscope (SP-STM) using a photoexcited GaAs tip has been expected to observe magnetic domains and surface spin structures with atomic spatial resolution. Spin-polarized electrons can be generated in the GaAs conduction band by circularly polarized light pumping. We developed GaAs microtips and are trying to realize the SP-STM system. In this paper, we report the influence of surface states of the GaAs microtip on the spin-dependent tunneling current. This effect is very important to obtain high sensitivity in the SP-STM using a GaAs tip.