Angular dependent magnetothermopower of α-(ET)₂KHg(SCN)₄

Abstract

The magnetic field and angular dependences of the thermopower and Nernst effect of the quasi-twodimensional (q2D) organic conductor α-(ET)₂KHg(SCN)₄ are experimentally measured at temperatures below (4 K) and above (9 K) the transition temperature to fields of 31 T. In addition, a theoretical model which involves a magnetic breakdown effect between the q1D and q2D bands is proposed in order to simulate the data. Analysis of the background components of the thermopower and Nernst effect imply that at low temperatures, in the CDW state, the properties of α-(ET)₂KHg(SCN)₄ are determined mostly by the orbits on the new open Fermi sheets. Quantum oscillations observed in the both thermoelectric effects, at fields above 8 T, originate only from the α orbit.