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

GaAs microtips were fabricated by anisotropic wet etching and sulfur passiv ation. Scanning tunneling microscope (STM) observation with atomic-order sp atial resolution was achieved using the GaAs microtips. Sulfur passivation was effective for the suppressing the surface states of the GaAs tip. For t he magnetized Ni thin film, the difference in tunneling current between rig ht and left circularly polarized light excitations was observed in the nega tive 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 p olarization response signal was attempted, and the possibility of spin-pola rized STM using circularly polarized-light-pumped GaAs microtips was reveal ed.