arXiv subjects

Sudhansu S. Mandal

Publications and source records attributed to Sudhansu S. Mandal.

57 records · Page 4Linked to original sources

arXiv1995

Novel Finite Temperature Conductivity in Quantum Hall Systems

We study quantum Hall systems (mainly the integer case) at finite temperatures and show that there is a novel temperature dependence even for a pure system, thanks to the `anomalous' nature of generators of translation. The deviation of Hall conductivity from its zero temperature value is controlled by a parameter $T_0 =πρ/m^\ast N$ which is sample specific and hence the universality of quantization is lost at finite temperatures.

cond-mat↗

arXiv1994

Quantum Hall Effects at Finite Temperatures

We study the finite temperature (FT) effects on integer quantum Hall effect (IQHE) and fractional quantum Hall effect (FQHE) as predicted by the composite fermion model. We find that at $T\neq 0$, universality is lost, as is quantization because of a new scale $T_0=πρ/m^\ast p$. We find that this loss is not inconsistent with the experimentally observed accuracies. While the model seems to work very well for IQHE, it agrees with the bulk results of FQHE but is shown to require refinement in its account of microscopic properties such as the effective mass. Our analysis also gives a qualitative account of the threshold temperatures at which the FQHE states are seen experimentally. Finally, we extract model independent features of quantum Hall effect at FT, common to all Chern-Simons theories that employ mean field ansatz.

cond-mat↗

arXiv1994

Chern-Simons Superconductivity at finite magnetic field

We study Chern-Simons (CS) superconductivity in the presence of uniform external magnetic field of {\it arbitrary strength} for a system of fermions in two spatial dimensions, which are minimally coupled both to the CS and Maxwell gauge fields. We have carried out the computation within the mean field ansatz. Analysing only the mean field (i.e., ignoring the fluctuations of the gauge fields), we find that chemical potential, susceptibility and magnetization show discontinuities for integer number of filled Landau levels. Taking into account the fluctuations of the gauge fields, we find that the masses of the excitations increase with the magnetic field, and that the presence of nonlinear magnetic susceptibilities show the absence of any critical or pseudo critical magnetic field. Finally, an interesting result is that, unlike ordinary superconductors, the system is magnetically asymmetric.

cond-mat↗