arXiv subjects

A. Bäker

Publications and source records attributed to A. Bäker.

3 recordsLinked to original sources

arXiv2001

Frequency dependent transport in the integer quantum Hall effect

The frequency dependent transport is investigated for a two-dimensional disordered system under QHE conditions. The real and imaginary parts of the conductivity are calculated numerically in linear response using a recursive Green function technique. The energy dependence of $σ_{xx}(E,ω)$ is obtained within the lowest Landau band. When the width of the system exceeds the characteristic length, $L_ω=(\hbarωρ(E))^{-1/2}$, the maximum of the real part of $σ_{xx}(E,ω)$ decays with frequency almost linearly which is different from the classical Drude behaviour.

cond-mat.mes-hall↗

arXiv1999

Frequency dependent conductivity in the integer quantum Hall effect

Frequency dependent electronic transport is investigated for a two-dimensional disordered system in the presence of a strong perpendicular static magnetic field. The ac-conductivity 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 $σ_{xx}(ω)$ 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 $σ_{xx}$-peak with frequency in the lowest Landau band is found to exhibit a scaling relation from which the critical exponent can be extracted.

cond-mat.dis-nn↗

arXiv1998

Quantum-Hall to insulator transition

The crossover from the quantum Hall regime to the Hall-insulator is investigated by varying the strength of the diagonal disorder in a 2d tight-binding model. The Hall and longitudinal conductivities and the behavior of the critical states are calculated numerically. We find that with increasing 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.

cond-mat.dis-nn↗