Giant angular-dependent Nernst effect in the quasi-one-dimensional organic conductor (TMTSF)₂PF₆

We present a detailed study of the Nernst effect S_zx in (TMTSF)₂PF₆ as a function of temperature, magnetic field magnitude, direction, and pressure. As previously reported there is a large resonantlike 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)₂PF₆, based on a Boltzmann transport model within the semiclassical approximation. The Boltzmann transport calculation fails to describe the experimental data. We suggest that the answer may lie in the field induced decoupling of the strongly correlated chains.