Competing Hyperfine and Spin-Orbit Couplings: Spin Relaxation in a Quantum Hall Ferromagnet

Abstract

Spin relaxation in a quantum Hall ferromagnet, where filling is $\nu =1,1/3,1/5,...$, can be considered in terms of spin wave annihilation/creation processes. Hyperfine coupling with the nuclei of the GaAs matrix provides spin non-conservation in the two-dimensional electron gas and determines spin relaxation in the quantum Hall system. This mechanism competes with spin-orbit coupling channels of spin-wave decay and can even dominate in a low-temperature regime where $T$ is much smaller than the Zeeman gap. In this case the spin-wave relaxation process occurs non-exponentially with time and does not depend on the temperature. The competition of different relaxation channels results in crossovers in the dominant mechanism, leading to non-monotonic behavior of the characteristic relaxation time with the magnetic field. We predict that the relaxation times should reach maxima at $B\simeq 18$T in the $\nu =1$ Quantum Hall system and at $B\simeq 12$T for that of $\nu =1/3$. We estimate these times as $\sim 10-30\mu$s and $\sim 2-5\mu$s, respectively.

26 pages, 1 figure

References in corpus (5)

• Transport in strongly correlated two dimensional electron fluids
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• Extra Spin-Wave mode in Quantum Hall systems. Beyond the Skyrmion Limit
• Goldstone Mode Relaxation in a Quantum Hall Ferromagnet due to Hyperfine Interaction with Nuclei
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• Stochastization of long living spin-cyclotron excitations in a spin-unpolarised quantum Hall system
• Spin-rotation mode in a quantum Hall ferromagnet
• Damping via the hyperfine interaction of a spin-rotation mode in a two-dimensional strongly magnetized electron plasma