SDW phase of (EDT-TTF)2AuBr2

The low temperature phase in (EDT-TTF)2AuBr2 was investigated by 1H NMR and magnetic susceptibility measurements for protonated and partially deuterated single crystals. Two sharp peaks were observed in the temperature dependence of T1-1 for both salts, associated with the SDW transition TSDW and the sub-phase transition T* common in the incommensurate SDW phase. The values of TSDW determined as 15 and 19 K for h- and d-salts, respectively, indicate the negative chemical pressure effect. The obtained ratios T*/TSDW 0.37 and 0.43 for h- and d-salts, respectively, are slightly larger than the common value T*/TSDW≅0.3 observed in (TMTCF)2X. The ratio T*/TSDW increases for larger TSDW and the low temperature sub-phase becomes more stable.