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Absorption in the fractional quantum Hall regime: trion dichroism and spin polarization

J. G. Groshaus·P. Plochocka-Polack·M. Rappaport·V. Umansky·I. Bar-Joseph·B. S. Dennis·L. N Pfeiffer·K. W. West·Y. Gallais·A. Pinczuk
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Abstract

We present measurements of optical interband absorption in the fractional quantum Hall regime in a GaAs quantum well in the range 0 < nu < 1. We investigate the mechanism of singlet trion absorption, and show that its circular dichroism can be used as a probe of the spin polarization of the ground state of the two-dimensional electron system (2DES). We find that at nu = 1/3 the 2DES is fully spin-polarized. Increasing the filling factor results in a gradual depolarization, with a sharp minimum in the dichroism near nu = 2/3. We find that in the range 0.5 < nu < 0.85 the 2DES remains partially polarized for the broad range of magnetic fields from 2.75 to 11 Tesla. This is consistent with the presence of a mixture of polarized and depolarized regions.

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J. G. Groshaus, P. Plochocka-Polack, M. Rappaport, V. Umansky, I. Bar-Joseph, B. S. Dennis, L. N Pfeiffer, K. W. West, Y. Gallais, A. Pinczuk. 2006-09-26. Absorption in the fractional quantum Hall regime: trion dichroism and spin polarization. https://doi.org/10.1103/physrevlett.98.156803

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