13C NMR investigation of low-temperature states in one-dimensional organic cation radical salt, (TMTTF)2SbF6, under high pressures

Abstract

13C nuclear magnetic resonance (NMR) measurements under the application of hydrostatic pressure were carried out on the one-dimensional organic conductor, (TMTTF)2SbF6, to investigate the competed antiferromagnetic and spin-singlet ground states. The charge-ordering (CO) transition temperature, TCO, (155 K at ambient pressure), decreased to 100 K under a pressure of 5 kbar, and was suppressed above 8 kbar. Under pressures between 5 kbar and 14 kbar, the low-pressure side antiferromagnetic state (AF-I) was suppressed. At the same time, a spin-gap phase was stabilized. Above 17 kbar, another antiferromagnetic phase appeared below approximately 15 ~ 20 K. A possible reentrant antiferromagnetic phase diagram is discussed from a microscopic point-of-view.