Electron spin lifetimes in Hg0.78Cd0.22 Te and InSb

We have made direct pump–probe measurements of spin lifetimes in long wavelength narrow-gap semiconductors at wavelengths between 4 and View the MathML source and from 4 to View the MathML source. In particular, we measure remarkably long spin lifetimes, View the MathML source, even at View the MathML source for epilayers of degenerate n-type InSb. In this material the mobility is approximately constant between 77 and View the MathML source, and we find that τs is approximately constant in this temperature range. In order to determine the dominant spin relaxation mechanism we have investigated the temperature dependence of τs in non-degenerate lightly n-type Hg0.78Cd0.22Te of approximately the same band gap as InSb, and find that τs varies from View the MathML source at View the MathML source to View the MathML source at View the MathML source. Our results, both in magnitude and temperature dependence of τs, imply that the Elliott–Yafet model dominates in these materials.