Quantum-Hall to insulator transition

The crossover from the quantum Hall regime to the Hall-insulator is investi gated by varying the strength of the diagonal disorder in a 2d tight-bindin g model (TBM). The Hall and longitudinal conductivities and the behavior of the critical states are calculated numerically. We find that with increasi ng disorder the current carrying states close to the band center disappear first. Simultaneously, the quantized Hall conductivity drops monotonically to zero also from higher quantized values. (C) 1998 Elsevier Science B.V. A ll rights reserved.