${}^{13}$C NMR study of the magnetic properties of the quasi-one-dimensional conductor (TMTTF)${}_{2}$SbF${}_{6}$

$^{13}$ C NMR study of the magnetic properties of the quasi-one-dimensional conductor (TMTTF) $_{2}$ SbF $_{6}$

F. Iwase, K. Sugiura, K. Furukawa, and T. Nakamura

Phys. Rev. B 84, 115140 – Published 26 September 2011

Abstract

Magnetic properties in the quasi-one-dimensional organic salt, (TMTTF) $_{2}$ SbF $_{6}$ , where TMTTF is tetramethyltetrathiafulvalene, are investigated by $^{13}$ C NMR under pressures. Antiferromagnetic phase transition at ambient pressure (AFI) is confirmed. Charge ordering is suppressed by pressure and is not observed under 8 kbar. For $5 < P < 20$ kbar, a sharp spectrum and the rapid decrease of the spin-lattice relaxation rate $1 / T_{1}$ were observed below about 4 K, which is attributed to a spin-gap transition. Above 20 kbar, an extremely broadened spectrum and a critical increase of $1 / T_{1}$ were observed. This indicates that the system enters into another antiferromagnetic phase (AFII) under pressure. The slope of the antiferromagnetic phase transition temperature $T_{AFII}$ , $d T_{AFII} / d P$ , is positive, while $T_{AFI}$ decreases with pressure. The magnetic moment is weakly incommensurate with the lattice at 30 kbar.