Gigahertz spin noise spectroscopy in n-doped bulk GaAs

Abstract

We advance spin noise spectroscopy to an ultrafast tool to resolve high-frequency spin dynamics in semiconductors. The optical nondemolition experiment reveals the genuine origin of the inhomogeneous spin dephasing in n-doped GaAs wafers at densities at the metal-to-insulator transition. The measurements prove in conjunction with depth-resolved spin noise measurements that the broadening of the spin dephasing rate does not result from thermal fluctuations or spin-phonon interaction, as suggested previously, but from spatial g -factor variations. © 2010 The American Physical Society.