Current Induced Nuclear Spin Depolarization at Landau Level Filling Factor nu=1/2

Abstract

Hyperfine interactions between electron and nuclear spins in the quantum Hall regime provide powerful means for manipulation and detection of nuclear spins. In this work we demonstrate that significant changes in nuclear spin polarization can be created by applying an electric current in a 2-dimensional electron system at Landau level filling factor nu=1/2. Electron spin transitions at nu= 2/3 and 1/2 are utilized for the measurement of the nuclear spin polarization. Consistent results are obtained from these two different methods of nuclear magnetometry. The finite thickness of the electron wavefunction is found to be important even for a narrow quantum well. The current induced effect on nuclear spins can be attributed to electron heating and the efficient coupling between the nuclear and electron spin systems at nu=1/2. The electron temperature, elevated by the current, can be measured with a thermometer based on the measurement of the nuclear spin relaxation rate. The nuclear spin polarization follows a Curie law dependence on the electron temperature. This work also allows us to evaluate the electron g-factor in high magnetic fields as well as the polarization mass of composite fermions.

13 pages, 11 figures

References in corpus (7)

• Unraveling the spin polarization of the v = 5/2 fractional quantum Hall state
• Spinful Composite Fermions in a Negative Effective Field
• Electrical polarization of nuclear spins in a breakdown regime of quantum Hall effect
• NMR Evidence for Spin Canting in a Bilayer nu = 2 Quantum Hall System
• Spin Transition in the Half-Filled Landau Level
• NMR Probing Spin Excitations in the Ring-Like Structure of a Two-Subband System
• Dynamic nuclear polarization induced by breakdown of fractional quantum Hall effect

Cited by in corpus (9)

• Counter-propagating charge transport in the quantum Hall effect regime
• Quantum Hall Spin Diode
• Dynamic nuclear polarization from current-induced electron spin polarization
• Spin and the Coulomb Gap in the Half-Filled Lowest Landau Level
• Effect of magnetization on the tunneling anomaly in compressible quantum Hall states
• Nuclear Magnetometry Study of Spin Dynamics in Bilayer Quantum Hall Systems
• Semiclassical theory of the tunneling anomaly in partially spin-polarized compressible quantum Hall states
• Interlayer Interactions and the Fermi Energy of Bilayer Composite Fermion Metals
• Disorder Enhanced Nuclear Spin Relaxation at Landau Level Filling Factor One