PROGRESS TOWARD SPIN-SENSITIVE SCANNING-TUNNELING-MICROSCOPY USING OPTICAL ORIENTATION IN GAAS

Advances toward spin-sensitive scanning tunneling microscopy are reported here, using optically created spin polarized electrons in GaAs. As a first step, tunneling spectroscopy has been performed on GaAs samples with light excitation. Dependence of photoinduced effects on excitation power, tip-sample distance, and doping density are presented. Similar measurements were conducted for a cleaved GaAs tip, showing short circuit currents of several hundred pA upon laser illumination. Results support the feasibility of using such tips as a spin-sensitive local probe.