Quantum Hall Transitions in (TMTSF)$_2$PF$_6$
  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. 
S. Valfells (1), J.S. Brooks (2), Z. Wang (1), S. Takasaki (3), J.   Yamada (3), H. Anzai (3), M. Tokumoto (4) ((1) Boston U...