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Free keywords:
fractional quantum Hall effect; phase transition; nuclear spin polarisation
Abstract:
The spin unpolarised to spin polarised v = 2/3 phase transition is
studied in narrow quantum wells. The phase transition is mapped in the
filling factor (v), density (n)-plane and is well described assuming a
rootn dependence of the Composite Fermion effective mass. At high
currents the huge longitudinal resistance anomaly appears along the
phase boundary. A model is presented that treats the current induced
nuclear spin polarisation as an additional source of disorder, which
drastically alters the initial domain structure present at the phase
boundary. Time and current dependent measurements at constant magnetic
field indicate that a large alternating Hall field is necessary to
maintain the high resistance state. (C) 2003 Elsevier B.V. All rights
reserved.
