Argument for charge density wave sub-phases in ground state of α-(BEDT-TTF)2KHg(SCN)4

A resistive anomaly at temperature T-p in the title compound is associated with a Fermi surface reconstruction from a metallic to a (spin or charge) density wave state. At high magnetic fields a corresponding feature in the magnetoresistance above a field B-K indicates the breaking of this state. We argue that T-p indicates a second order phase line identical to that measured by specific heat methods and show that it decreases monotonically up to 30 T. We find that Pauli (rather than orbital) effects, dominate the reduction in T-p. We further argue that B-K is a first-order transition between two subphases below T-p. We compare the phase diagram with recent theoretical models for CDW and SDW ground states in high magnetic fields. (C) 1998 Elsevier Science Ltd. All rights reserved.