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Science 31 July 1998:
Vol. 281. no. 5377, pp. 686 - 690
DOI: 10.1126/science.281.5377.686
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Reports

Ultraslow Electron Spin Dynamics in GaAs Quantum Wells Probed by Optically Pumped NMR

N. N. Kuzma, P. Khandelwal, S. E. Barrett, * L. N. Pfeiffer, K. W. West

Optically pumped nuclear magnetic resonance (OPNMR) measurements were performed in two different electron-doped multiple quantum well samples near the fractional quantum Hall effect ground state nu  = 1/3. Below 0.5 kelvin, the spectra provide evidence that spin-reversed charged excitations of the nu  = 1/3 ground state are localized over the NMR time scale of about 40 microseconds. Furthermore, by varying NMR pulse parameters, the electron spin temperature (as measured by the Knight shift) could be driven above the lattice temperature, which shows that the value of the electron spin-lattice relaxation time tau 1s is between 100 microseconds and 500 milliseconds at nu  = 1/3.

N. N. Kuzma, P. Khandelwal, S. E. Barrett, Department of Physics, Yale University, New Haven, CT 06511, USA. L. N. Pfeiffer and K. W. West, Lucent Technologies, Bell Laboratories, Murray Hill, NJ 07974, USA.
*   To whom correspondence should be addressed.

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
All-Optical Magnetic Resonance in Semiconductors.
J. M. Kikkawa and D. D. Awschalom (2000)
Science 287, 473-476
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