Diffusion of electrons in a two-dimensional system in static random magnetic fields is studied by solving the time-dependent Schrödinger equation numerically. The asymptotic behaviors of the second moment of the wave packets and the temporal autocorrelation function in such systems are investigated. It is shown that, in the region away from the band edge, the growth of the second moment of the wave packets turns out to be diffusive, whereas the exponents for the power-law decay of the temporal autocorrelation function suggest a kind of fractal structure in the energy spectrum and in the wave functions. The present results are consistent with the interpretation that the states away from the band edge region are critical.

• Received 28 December 1994

DOI:https://doi.org/10.1103/PhysRevB.51.10897