Spin and anion dynamics on (TMTSF)2 FSO3, studied by NMR

Abstract

In order to characterise the electronic properties in sub-phases of (TMTSF)2FSO3 under pressure, 77Se, and 19F NMR Knight shift (K) and relaxation rate (1/T1) measurements were performed at ambient and 0.82 GPa pressure.The insulating phase below the metal-insulator transition (MIT) at 89 K at ambient pressure (AP) was confirmed as a nonmagnetic state with a gap of Δ/k B∼420 K. This MIT is strongly coupled with anion ordering.The MIT temperature decreases under pressure, and many electronic anomalies (or transitions) have been observed from transport measurements.The reduction of density of states in the metallic state by applying pressure was confirmed by the analysis of K and Korringa constant (1/T1T). A nonmagnetic insulating transition corresponding to the MIT at AP at 89 K, was observed at ∼45K at 0.82 GPa. A spin (charge) gap in the insulating state at 0.82 GPa is smaller (Δ/kB∼90 K) than that at AP. © EDP Sciences.