Electron–nuclear double resonance and dynamic nuclear polarization in GaAs in the regime of the quantum Hall effect

Electron spin resonance (ESR) and electron-nuclear double resonance experiments were performed in the 2D electron systems of GaAs/AlxGa1−xAs quantum well and heterojunction samples in the vicinity of the unity filling factor in the regime of the quantum Hall effect. As is well known, the ESR response is strongly affected by the local nuclear fields induced by dynamic nuclear polarization. The peculiar resistance responses resulting from dynamic nuclear polarization and NMR were numerically simulated on the basis of the rate equation for the Zeeman order of nuclei in the vicinity of the 2D electron system. The simulations, which include the nuclear spin diffusion, provide an opportunity to visualize the propagation of the nuclear spin polarization into the AlxGa1−xAs barriers of the quantum wells.