Physical Review Letters -- January 24, 2000 -- Volume 84, Issue 4 pp. 725-728
We investigate the double-layer electron system in a parabolic quantum well at filling factor n = 2 in a tilted magnetic field using capacitance spectroscopy. The competition between two ground states is found at the Zeeman splitting appreciably smaller than the symmetric-antisymmetric splitting. Although at the transition point the system breaks up into domains of the two competing states, the activation energy turns out to be finite, signaling the occurrence of a new insulator-insulator quantum phase transition. We interpret the obtained results in terms of a predicted canted antiferromagnetic phase.
KeyWords: semiconductor quantum wells; magnetic field effects; antiferrimagnetism; capacitance; ground states; Zeeman effect; spontaneous symmetry breaking; phase transformations
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