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Paper IPM / Physic / 6810 |
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Abstract: | |||||||||
We present a variational study of both unpaired and spin-singlet paired states induced in a two-dimensional electron gas at low density by a perpendicular magnetic field. It is based on an improved circular-cell approximation which leads to a number of closed analytical results. The ground-state energy of the Wigner crystal containing a single electron per cell in the lowest Landau level is obtained as a function of the filling factor ν: the results are in good agreement with those of earlier approaches and predict νc ≈ 0.25 for the upper filling factor at which the solid-liquid transition occurs. A novel localized state of spin-singlet electron pairs is examined and found to be a competitor of the unpaired state for filling factor ν > 1. The corresponding phase boundary is quantitatively displayed in the magnetic field-electron density plane.
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