Competing phases in the high field phase diagram of (TMTSF)$_2$ClO$_4$

TL;DR

This paper models the high field phase diagram of (TMTSF)$_2$ClO$_4$, highlighting the competition between different nesting processes and explaining the observed phase transitions between N=0 and N=1 phases.

Contribution

It introduces a model considering anion ordering and Fermi surface splitting to explain phase competition in (TMTSF)$_2$ClO$_4$ under high magnetic fields.

Findings

N=0 phase dominates at high fields due to intraband nesting.

A first order transition occurs from N=0 to N=1 phase at lower temperatures.

The model reproduces experimentally observed phase diagrams.

Abstract

A model is presented for the high field phase diagram of (TMTSF)$_2$ClO$_4$, taking into account the anion ordering, which splits the Fermi surface in two bands. For strong enough field, the largest metal-SDW critical temperature corresponds to the N=0 phase, which originates from two intraband nesting processes. At lower temperature, the competition between these processes puts at disadvantage the N=0 phase vs. the N=1 phase, which is due to interband nesting. A first order transition takes then place from the N=0 to N=1 phase. We ascribe to this effect the experimentally observed phase diagrams.