Creation and detection of spin-polarized current in the scanning-tunneling-microscope

Spin polarization of carriers was studied when the carriers were being transported from a non-magnetic scanning-tunneling-microscope tip to a GaAs substrate through a ferromagnetic nanostructure at room temperature. The spin polarization was estimated by measuring the circular polarization of light created by a radiative recombination of the carriers in the GaAs sample. The circular polarization measured shows that non-spin-polarized carriers in the non-magnetic PtIr tip changed to spin-polarized ones in the GaAs substrate when they were transported through thin Fe layers. The high spin polarization of the carriers was caused by the unoccupied state of minority-band of the Fe layer and suggests a promising method to achieve spintronic devices at room temperature.