Relaxation of Optically Pumped Electron Spins through a Virtual Photon: Experimental Evidence in Heavily Zn-Doped GaAs

Abstract

A new mechanism is described for the spin relaxation of photoelectrons in $p$-type semiconductors through the electromagnetic coupling to virtual photons. For the degenerate case the result approaches a limit independent of hole density and temperature, distinguishing this mechanism from all others that have been proposed. Experimental results on optically pumped Zn-doped GaAs (5×${10}^{17}$ to 2×${10}^{19}$ ${\mathrm{cm}}^{-3\mathrm{}}$) are presented which confirm the existence of such a regime with ${\tau }_s\sim 1.5\times {10}^{-9\mathrm{}}$ s.