Temperature and doping dependence of spin relaxation in n -InAs

We have used time-resolved spectroscopy to measure the relaxation of spin polarizations in the narrow gap semiconductor material n -InAs as a function of temperature, doping, and pump wavelength. The results are consistent with the D'Yakonov-Perel mechanism for temperatures between 77 and 300 K. However, the data suggest that electron-electron scattering should be taken into account in determining the dependence of the spin lifetime on the carrier concentration in the range 5.2× 1016 -8.8× 1017 cm-3. For a sample with doping of 1.22× 1017 cm-3 the spin lifetime was 24 ps at room temperature. By applying a magnetic field in the sample plane we also observed coherent precession of the spins in the time domain, with a g factor g* =-13, also at room temperature. © 2005 The American Physical Society.