Fabrication of GaAs microtips and their application to spin-polarized scanning tunneling microscope

GaAs microtips were fabricated by anisotropic wet etching and sulfur passivation. Scanning tunneling microscope (STM) observation with atomic-order spatial resolution was achieved using the GaAs microtips. Sulfur passivation was effective for the suppressing the surface states of the GaAs tip. For the magnetized Ni thin film, the difference in tunneling current between right and left circularly polarized light excitations was observed in the negative tip bias region and was found to depend on the magnetization direction. This result suggests that the polarization response signal is related to the spin structure of the magnetized Ni thin-film surface; Imaging of the polarization response signal was attempted, and the possibility of spin-polarized STM using circularly polarized-light-pumped GaAs microtips was revealed.