Electron-nuclear spin interaction in edge states of quantum Hall systems

We have studied the electron-nuclear spin interaction in integer and fractional quantum- Hall edge channels. By selectively populating edge channels of different spin polarities, nuclear spins along the edge channels are dynamically polarized through the hyperfine interaction. The resultant dynamic nuclear polarization is detected with the edge-channel transport via nuclear magnetic resonance. The technique of controlling and detecting nuclear-spin polarization in quantum-Hall systems opens up new possibilities of developing nuclear-spin solid-state devices as well as shedding new light to spin properties of quantum-Hall systems. We demonstrate local controllability of the nuclear-spin polarization using a built-in micro-metal strip fabricated on a quantum-Hall device. We also demonstrate that the dynamic nuclear polarization can be utilized as a sensitive probe of the spin polarization of fractional quantum-Hall edge channels.