Quantum electronic phases in partially filled Landau levels

Abstract
On the basis of energy calculations, we investigate the competition between quantum-liquid and electron-solid phases in intermediate Landau levels as a function of their partial filling factor. An alternation of electron-solid phases, which are insulating because they are pinned by the residual impurities in the sample, and quantum liquids displaying the fractional quantum Hall effect explains an observed reentrance of the integral quantum Hall effect. The phase transitions are identified as first-order. Recent transport measurements under micro-wave irradiation reveal the crystalline origin of the reentrant points, and a mixed phase of a coexisting Wigner crystal and a 2-electron bubble phase is found in a Landau-level filling-factor range , as expected from our calculations.