Suppression of a charge density wave ground state in high magnetic fields: spin and orbital mechanisms

TL;DR

This study investigates how high magnetic fields suppress the charge density wave state in a quasi-one-dimensional organic material, revealing spin and orbital effects that influence the transition and electronic behavior.

Contribution

It provides experimental evidence of magnetic field effects on CDW suppression, highlighting the roles of spin and orbital mechanisms in a Q1D organic compound.

Findings

CDW transition temperature decreases with magnetic field

Suppression of CDW occurs around 37 T at low temperatures

Orbital effects emerge above 15 T when field is tilted

Abstract

The charge density wave (CDW) transition temperature in the quasi-one dimensional (Q1D) organic material of (Per)$_2$Au(mnt)$_2$ is relatively low (TCDW = 12 K). Hence in a mean field BCS model, the CDW state should be completely suppressed in magnetic fields of order 30 - 40 T. To explore this possibility, the magnetoresistance of (Per)$_2$Au(mnt)$_2$ was investigated in magnetic fields to 45 T for 0.5 K < T < 12 K. For fields directed along the Q1D molecular stacking direction, TCDW decreases with field, terminating at about ~ 37 T for temperatures approaching zero. Results for this field orientation are in general agreement with theoretical predictions, including the field dependence of the magnetoresistance and the energy gap, $\Delta_{CDW}$. However, for fields tilted away from the stacking direction, orbital effects arise above 15 T that may be related to the return of un-nested Fermi surface sections that develop as the CDW state is suppressed. These findings are consistent with expectations that quasi-one dimensional metallic behavior will return outside the CDW phase boundary.