Use of a gaas microprobe tip pumped by circularly polarized light as a source of spin‐polarized tunneling electrons

Abstract

AbstractWe have studied the feasibility of using GaAs microprobe tips fabricated by anisotropic wet chemical etching followed by sulfur passivation as a source of spin‐polarized tunneling electrons. In our experiments, we studied the magnetic state of a nickel thin film by spin‐polarized STM, using a GaAs microprobe tip illuminated by circularly polarized light. We observed that the tunneling current was different depending on the sense of rotation of the circular polarization (and hence was proportional to the number of spin‐polarized tunneling electrons). We then made measurements of the thin film's hysteresis characteristics by the same technique and by the magnetic Kerr effect. We confirmed by time‐resolved photoluminescence measurements that surface states located at the surface of the GaAs microprobe tip can mediate the tunneling, which shortens the lifetime of electrons within the tip. This indicates that these surface states can affect the spin‐polarized tunneling signal. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 85(5): 21–28, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1103