Experimental Demonstration of Room-Temperature Spin Transport in n-Type Germanium Epilayers

Abstract

次世代半導体材料ゲルマニウムにおける室温スピン伝導を世界で初めて実現.京都大学プレスリリース. 2015-04-27.We report an experimental demonstration of room-temperature spin transport in n-type Ge epilayers grown on a Si(001) substrate. By utilizing spin pumping under ferromagnetic resonance, which inherently endows a spin battery function for semiconductors connected with a ferromagnet, a pure spin current is generated in the n−Ge at room temperature. The pure spin current is detected by using the inverse spin-Hall effect of either a Pt or Pd electrode on n−Ge. From a theoretical model that includes a geometrical contribution, the spin diffusion length in n−Ge at room temperature is estimated to be 660 nm. Moreover, the spin relaxation time decreases with increasing temperature, in agreement with a recently proposed theory of donor-driven spin relaxation in multivalley semiconductors