ARGUMENT FOR CHARGE-DENSITY-WAVE SUB-PHASES IN-GROUND STATE OF ALPHA-(BEDT-TTF)(2)KHG(SCN)(4)

A resistive anomaly at temperature T-p in the title compound is associ ated with a Fermi surface reconstruction from a metallic to a (spin or charge) density wave state. At high magnetic fields a corresponding f eature in the magnetoresistance above a field B-K indicates the breaki ng of this state. We argue that T-p indicates a second order phase lin e identical to that measured by specific heat methods and show that it decreases monotonically up to 30 T. We find that Pauli (rather than o rbital) 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 co mpare 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.