77Se NMR study of nonmagnetic–magnetic transition in (TMTSF)2X

Se-77 NMR measurements have been carried out on (TMTSF)(2)X (X = PF6 and AsF6) single crystals. For both compounds, NMR lines split into double-peaked spectra in the SDW state, which is explained with sinusoidal internal field at Se nucleus positions having the same incommensurate wave number with that of the SDW order. No change in the lineshape was observed at T-x at which the spin-relaxation rate shows a kink, suggesting that this anomaly does not cause significant static changes in internal field at the Se-site. (C) 2009 Elsevier B.V. All rights reserved.