Frequency dependent conductivity in the integer quantum Hall effect

Abstract. Frequency dependent electronic transport is investigated for a two-dimensional disordered system in the presence of a strong perpendicular static magnetic field. The acconductivity is calculated numerically from Kubo’s linear response theory using a recursive Green’s function technique. In the tail of the lowest Landau band, we find a linear frequency dependence for the imaginary part of σxx(ω) which agrees well with earlier analytical calculations. On the other hand, the frequency dependence of the real part can not be expressed by a simple power law. The broadening of the σxx-peak with frequency in the lowest Landau band is found to exhibit a scaling relation from which the critical exponent can be extracted.