Field-induced spin-density-wave phases in TMTSF organic conductors: quantization versus non-quantization
Abstract
We study the magnetic-field-induced spin-density-wave (FISDW) phases in TMTSF organic conductors in the framework of the quantized nesting model. In agreement with recent suggestions, we find that the SDW wave-vector
Q
deviates from its quantized value near the transition temperature
T
c
for all phases with quantum numbers
N>0
. Deviations from quantization are more pronounced at low pressure and higher
N
and may lead to a suppression of the first-order transitions
N+1→N
for
N≥5
. Below a critical pressure, we find that the N=0 phase invades the entire phase diagram in accordance with earlier experiments. We also show that at T=0, the quantization of
Q
and hence the Hall conductance is always exact. Our results suggest a novel phase transition/crossover at intermediate temperatures between phases with quantized and non-quantized
Q
.