Role of the dimerized gap due to anion ordering in spin-density wave phase of (TMTSF)$_2$ClO$_4$ at high magnetic fields

TL;DR

This study investigates how anion ordering-induced dimerized gaps influence the spin-density wave phases in (TMTSF)$_2$ClO$_4$ under high magnetic fields, revealing the impact of cooling rates on phase boundaries and stability.

Contribution

It demonstrates that the dimerized gap from anion ordering significantly affects FISDW phase boundaries and transitions, a novel insight into the material's electronic phase behavior.

Findings

Cooling rate shifts the high field phase boundary $eta_{ m {HI}}$ to lower fields.

Increased cooling rate suppresses the semimetallic SDW phase.

The dimerized gap stabilizes a peculiar SDW nesting vector.

Abstract

Magnetoresistance measurements have been carried out along the highly conducting a axis in the FISDW phase of hydrogened and deuterated (TMTSF)$_2$ClO$_4$ for various cooling rates through the anion ordering temperature. With increasing the cooling rate, a) the high field phase boundary $\beta_{\rm {HI}}$, observed at 27 T in hydrogened samples for slowly cooled, is shifted towards a lower field, b) the last semimetallic SDW phase below $\beta_{\rm {HI}}$ is suppressed, and c) the FISDW insulating phase above $\beta_{\rm {HI}}$ is enhanced in both salts. The cooling rate dependence of the FISDW transition and of $\beta_{\rm {HI}}$ in both salts can be explained by taking into account the peculiar SDW nesting vector stabilized by the dimerized gap due to anion ordering.