Temperature dependence of the electron spin g factor in GaAs

The temperature dependence of the electron spin g factor in GaAs is investigated experimentally and theoretically. Experimentally, the g factor was measured using time-resolved Faraday rotation due to Larmor precession of electron spins in the temperature range between 4.5 and 190 K. The experiment shows an almost linear increase in the g value with the temperature. This result is in good agreement with other measurements based on photoluminescence quantum beats and time-resolved Kerr rotation up to room temperature. The experimental data are described theoretically taking into account a diminishing fundamental energy gap in GaAs due to lattice thermal dilatation and nonparabolicity of the conduction band calculated using a five-level k ? p model. According to the model, the g factor increases when the electron energy increases in the band with the growing Landau level n and the wave vector kz. At higher temperatures electrons populate higher Landau levels and the average g factor is obtained from a summation over many levels and an integration over kz. A very good description of the experimental data is obtained indicating that the observed increase in the spin g factor with the temperature is predominantly due to band's nonparabolicity. © 2008 The American Physical Society.