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AlAs 2DES; quantum Hall effects; quantum Hall ferromagnetism
Abstract:
We present magneto-transport measurements in tilted magnetic fields on
high mobility (mu = 300.000 cm(2)/V s) AlAs two-dimensional electron
systems. Our samples show integer and fractional quantum Hall effects.
In titled magnetic fields, at the crossings of Landau levels with
opposite spin, the resistance shows a spike if the crossing occurs near
integer filling or is significantly enhanced otherwise. The position of
the spike displays a hysteresis below 350 mK that reaches more than 0.1
T at 20 mK. From the position of the crossing in the (B-tot,
B-perp)-plane the difference in exchange energy of the crossing levels
is determined and found to be a non-linear function of the
perpendicular magnetic field. (C) 2003 Elsevier B.V. All rights
reserved.
