Spin-polarized tunneling by spin-polarized scanning tunneling microscopy

Abstract

A spin-polarized scanning tunneling microscope (STM) using a GaAs tip has been studied to observe the magnetization with nanoscale resolution for a sample magnetized in the plane of the film. A STM image of Si(111) $\text{7×7}$ surface reconstruction using the GaAs tip was observed clearly under ultra-high-vacuum conditions. We found that the cleaved GaAs tip has a capability of high atomic resolution. Next, circularly polarized light irradiated the GaAs tip, and the $\mathrm{I–V}$ characteristics were measured for magnetic ${\mathrm{Ni}}_{\mathrm{80}}{\mathrm{Fe}}_{\mathrm{20}}$ and nonmagnetic Au samples. Changes in the tunneling current, which is estimated to be approximately 7%, were observed only for the NiFe sample under the circularly polarized light irradiation. It suggests that the change in the tunneling current is due to the spin-polarized tunneling from the GaAs tip to the NiFe.