Giant Angular Dependent Nernst Effect in the Q1D Organic conductor (TMTSF)$_2$PF$_6$

TL;DR

This paper investigates the angular dependence of the Nernst effect in the quasi-one-dimensional organic conductor (TMTSF)$_2$PF$_6$, revealing resonant features linked to crystallographic directions and suggesting complex underlying transport mechanisms.

Contribution

It provides detailed experimental data on the Nernst effect and compares it with Boltzmann transport calculations, proposing field-induced decoupling as a key factor.

Findings

Large resonant Nernst signals at Lebed Magic Angles

Boltzmann model fails to explain the data

Field-induced decoupling of chains may be responsible

Abstract

We present a detailed study of the Nernst effect N$_{zx}$ in (TMTSF)$_2$PF$_6$ as a function of temperature, magnetic field magnitude and direction and pressure. As previously reported there is a large resonant-like structure as the magnetic field is rotated through crystallographic directions, the Lebed Magic Angles. These Nernst effect resonances strongly suggest that the transport of the system is effectively ``coherent'' only in crystallographic planes along or close to the applied field direction. We also present analytical and numerical calculations of the conductivity and thermoelectric tensors for (TMTSF)$_2$PF$_6$, based on a Boltzmann transport model within the semi-classical approximation. The Boltzmann transport calculation fails to describe the experiment data. We suggest that the answer may lie in field induced decoupling of the strongly correlated chains.