ESR investigation of the low temperature state in α-(BEDT-TTF)2KHg(SCN)4

Abstract We have performed ESR measurements on an α-(BEDT-TTF) 2 KHg(SCN) 4 single crystal at temperatures down to 0.9 K. Two regions where the ESR intensity decreases were observed. One corresponds to the proposed SDW transition ( T ≈9 K); the other takes place at T ≤2 K. A new resonance line appears below the transition temperature T≈9 K; its intensity grows continuously as the temperature is lowered. We regard the decrease of the ESR line at very low temperatures as evidence of a further phase transition.