Magnetoresistance of composite fermions at \nu=1/2

TL;DR

This study investigates the temperature dependence of resistivity near filling factor 1/2 in composite fermions, revealing positive magnetoresistance with minimal temperature effects and no change in Hall resistivity, challenging existing mean-field theories.

Contribution

The paper provides experimental data showing deviations from mean-field theory predictions, suggesting the importance of gauge field fluctuations in composite fermion interactions.

Findings

Magnetoresistance is positive and nearly temperature-independent.

Hall resistivity shows no measurable temperature correction.

Results challenge mean-field composite fermion theory, indicating gauge field fluctuations may be significant.

Abstract

We have studied temperature dependence of both diagonal and Hall resistivity in the vicinity of $\nu=1/2$. Magnetoresistance was found to be positive and almost independent of temperature: temperature enters resistivity as a logarithmic correction. At the same time, no measurable corrections to the Hall resistivity has been found. Neither of these results can be explained within the mean-field theory of composite fermions by an analogy with conventional low-field interaction theory. There is an indication that interactions of composite fermions with fluctuations of the gauge field may reconcile the theory and experiment.