Optically detected conduction electron spin resonance, overhauser shift and nuclear magnetic resonance in p-GaAlAs/GaAs heterostructures

Abstract The spin resonance of the conduction electrons in a single GaAlAs/GaAs heterostructure has been detected by measuring the degree of circular polarization of the luminescence in a microwave magnetic resonance field at 8.4 GHz. The effective g-factor is g ∗ = −0.47 ± 0.01, slightly different from the bulk value ≈ − 0.44. Additionally, the shift of the conduction electron spin resonance frequency due to the polarization of nuclei ( Overhauser shift ) has been observed for the first time in a single heterostructure. Additionally, the nuclear magnetic resonance can be observed directly by this very sensitive optical method because of the coupling of the nuclear spins to those of the conduction electrons. Lineshapes and intensities of the NMR signals depend on pumping light intensity and polarization. The measured relaxation rates of the different nuclei were found to be consistent with the results from the Overhauser shift. For the optical detection of both Overhauser shift and NMR, only nuclei which overlap with the wave function of conduction electrons near the GaAl-As/GaAs interface contribute to the measured signal.