Evolution of spin coherence dynamics and g factor with electron excess energy in bulk intrinsic GaAs

Circularly polarized absorption quantum-beat spectroscopy is used to study excess-energy dependence of electron-spin coherence dynamics in intrinsic GaAs. Absorption quantum beats are observed. The quantum-beat oscillatory frequency is used as a high precision measure of electron g factor. Double linear energy dependence of g factor is obtained and disagrees with the prediction of k∙p theory. A theoretical calculation reveals the double linear energy dependence reflects the energy dependence of g factor of electrons measured through light-hole- and heavy-hole-electron transitions, respectively. The phase of the quantum beats provides the key information to distinguish the two transitions experimentally.