Condensed Matter Physics Seminar

Thursday, April 13, 2000, 2 p.m.
Plant Sciences Building, Room 1130

Ferromagnetic Ordering and Relaxation in the Fractional Quantum Hall Regime of a Two Dimensional Electron System

Woowon Kang

(Department of Physics, University of Chicago)

Abstract:  In the study of the fractional quantum Hall effect (FQHE) states in the limit of negligible Zeeman energy, the degeneracy between the spin-polarized and spin-unpolarized FQHE leads to an emergence of a novel two-dimensional ferromagnet.  This ordering transition to a quantum Hall ferromagnet is found over a range of pressure above and below the critical pressure at which a  spin transition is found.  The ordered state exhibits an unusual hysteresis and relaxation in the vicinity of the ordered phases.  The magnetoresistance in the ferromagnetic region can either grow or decay logarithmically with time and an intriguing correlation with the hysteretic behavior is found.  These results are consistent with the  presence of a complex domain structure in the magnetically ordered quantum Hall states.

Host: Victor Yakovenko

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