Optical Detection of Dynamic Polarization of Nuclei in Semiconductors

Abstract

Much research has been performed by now on optical pumping of spin-polarized electrons in semiconductors [1–6]. In these experiments, the spin-oriented carriers were excited from the valence band into the conduction band by absorption of circularly-polarized light. The most convenient for the detection of the spin orientation of the electrons is an optical method [2, 3] with investigation of the recombination-luminescence polarization. For III–V crystals, the selection rules for interband transitions yield a simple connection S = 0.5P between the degree of circular polarization of the luminescence (S) and the degree of stationary orientation of the electrons (P) at the bottom of the conduction band. We have investigated, also by an optical method, a number of effects that arise when the electron spins interact strongly with the magnetic moments of the nuclei in the crystal.