Spin dephasing of fluorine-bound electrons in ZnSe

Abstract

The spin coherence of an ensemble of electrons bound to fluorine donors in epitaxially grown ZnSe layers is studied by time-resolved pump-probe Kerr rotation. Long-lived spin dephasing with decay times up to ${T}_{2}^{*}=33$ ns is found for a sample with a low fluorine concentration of $1\ifmmode\times\else\texttimes\fi{}{10}^{15}$ cm${}^{\ensuremath{-}3}$ at cryogenic temperatures. The time is close to the limit set by nuclear-spin fluctuations, for which we measure a strength of 1.65 mT. We find ${T}_{2}^{*}$ to be constant up to 40 K, with a strong drop for higher temperatures. The dephasing time also shortens with increasing fluorine concentration, indicating an interaction between the spins at different fluorine centers.