Metastable phase in the quantum Hall ferromagnet
  Time-dependent capacitance measurements reveal an unstable phase of electrons in gallium arsenide quantum well that occurs when two Landau levels with opposite spin are brought close to degeneracy by applying a gate voltage. This phase emerges below a critical temperature and displays a peculiar non-equilibrium dynamical evolution. The relaxation dynamics is found to follow a stretched exponential behavior and correlates with hysteresis loops observed by sweeping the magnetic field. These experiments indicate that metastable randomly-distributed magnetic domains are involved in the relaxation process in a way that is equivalently tunable by a change in gate voltage or temperature. 
Vincenzo Piazza (1), Vittorio Pellegrini (1), Fabio Beltram (1) and   Werner Wegscheider (2,3) ((1) NEST-INFM and Scuola Nor...