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
(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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