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Optically Pumped NMR Measurements of the Electron Spin Polarization in GaAs Quantum Wells near Landau Level Filling Factor nu=1/3

P. Khandelwal·N. N. Kuzma·S. E. Barrett·L. N. Pfeiffer·K. W. West
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Abstract

The Knight shift of Ga-71 nuclei is measured in two different electron-doped multiple quantum well samples using optically pumped NMR. These data are the first direct measurements of the electron spin polarization, P(nu,T)= /max , near nu=1/3. The P(T) data at nu=1/3 probe the neutral spin-flip excitations of a fractional quantum Hall ferromagnet. In addition, the saturated P(nu) drops on either side of nu=1/3, even in a Btot=12 Tesla field. The observed depolarization is quite small, consistent with an average of about 0.1 spin-flips per quasihole (or quasiparticle), a value which does not appear to be explicable by the current theoretical understanding of the FQHE near nu=1/3.

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P. Khandelwal, N. N. Kuzma, S. E. Barrett, L. N. Pfeiffer, K. W. West. 1998-07-20. Optically Pumped NMR Measurements of the Electron Spin Polarization in GaAs Quantum Wells near Landau Level Filling Factor nu=1/3. https://doi.org/10.1103/physrevlett.81.673

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