Quantum Hall Transitions in (TMTSF)$_2$PF$_6$

TL;DR

This study investigates the temperature dependence of quantum Hall transitions in (TMTSF)$_2$PF$_6$, revealing non-universal scaling and BCS-like behavior linked to the spin-density wave gap.

Contribution

It presents the first detailed analysis of quantum Hall transitions in a molecular crystal, showing deviations from universal scaling laws and connecting behavior to the material's order parameter.

Findings

Transition width does not follow universal power-law scaling.

Slope of $ ho_{xy}$ risers shows BCS-like temperature dependence.

$ ho_{xx}$ peak width inversely correlates with temperature.

Abstract

We have studied the temperature dependence of the integer quantum Hall transitions in the molecular crystal (TMTSF)$_2$PF$_6$. We find that the transition width between the quantum Hall plateaus does not exhibit the universal power-law scaling behavior of the integer quantum Hall effect observed in semiconducting devices. Instead, the slope of the $\rho_{xy}$ risers, $d\rho_{xy}/dB$, and the (inverse) width of the $\rho_{xx}$ peaks, $(\Delta B)^{-1}$, show a BCS-like energy gap temperature dependence. We discuss these results in terms of the field-induced spin-density wave gap and order parameter of the system.