Field-induced spin-density-wave phases in TMTSF organic conductors: quantization versus non-quantization

TL;DR

This paper investigates the behavior of spin-density-wave phases in TMTSF organic conductors under magnetic fields, revealing deviations from quantization near transition temperatures and a transition to exact quantization at zero temperature.

Contribution

It demonstrates that the SDW wave-vector deviates from quantization near transition temperatures and becomes exact at zero temperature, providing new insights into phase transitions in these materials.

Findings

Deviations from quantization occur near transition temperature for N>0 phases.

At zero temperature, the wave-vector quantization and Hall conductance are exact.

A phase transition or crossover exists between quantized and non-quantized phases at intermediate temperatures.

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 ${\bf Q}$ 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 $N+1\to N$ for $N\ge 5$. 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 ${\bf Q}$ 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 ${\bf Q}$.