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Microwave resonances of the bubble phases in 1/4 and 3/4 filled higher Landau levels

R. M. Lewis·P. D. Ye·L. W. Engel·D. C. Tsui·L. N. Pfeiffer·K. W. West
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Abstract

We have measured the diagonal conductivity in the microwave regime of an ultrahigh mobility two dimensional electron system. We find a sharp resonance in Re[sigma_{xx}] versus frequency when nu > 4 and the partial filling of the highest Landau level, nu^*, is ~ 1/4 or 3/4 and temperatures < 0.1 K. The resonance appears for a range of nu^* from 0.20 to 0.37 and again from 0.62 to 0.82. the peak frequency, f_{pk} changes from ~ 500 to ~ 150 as nu^* = 1/2 is approached. This range of f_{pk} shows no dependence on nu where the resonance is observed. The quality factor, Q, of the resonance is maximum at ~ nu^* = 0.25 and 0.74. We interpret the resonance as due to a pinning mode of the bubble phase crystal.

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R. M. Lewis, P. D. Ye, L. W. Engel, D. C. Tsui, L. N. Pfeiffer, K. W. West. 2002-07-31. Microwave resonances of the bubble phases in 1/4 and 3/4 filled higher Landau levels. https://doi.org/10.1103/physrevlett.89.136804

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