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

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 $\ddot{I}{}_{xy}$ risers, $d\ddot{I}{}_{xy}/dB$, and the (inverse) width of the $\ddot{I}{}_{xx}$ peaks, $(\hat{I}”B{)}^{-1}$, 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.

10 pages, RevTeX, 4 PostScript figures