Critical behavior at the metal-insulator transition in three-dimensional disordered systems in a strong magnetic field

The critical behavior of three-dimensional disordered systems in a strong magnetic field is investigated by analyzing the spectral fluctuations of the energy spectrum. The level spacing distribution P(s), as well the Dyson-Mehta statistics ${\mathrm{\Delta }}_3$(L), are considered. Except for the small s behavior of P(s), which depends on the presence or absence of a magnetic field but not on its strength, the other quantities, large s behavior of P(s) and ${\mathrm{\Delta }}_3$(L) turn out to be independent of its presence or absence and therefore of the time reversal symmetry. This suggests that the metal-insulator transition, which is defined by the symmetry of the system at the critical point, is independent of the presence or absence of the time reversal symmetry. © 1996 The American Physical Society.