NMR study of the antiferromagnetic to superconductor phase transition in (TMTSF)2PF6

The pressure-tuned quantum phase transition from spin-density wave (SDW) to Fermi Liquid (FL) ground states is studied in (TMTSF)(2)PF6 by NMR relaxation and spectroscopy. As for recent transport measurements, we find evidence in the distribution of local hyperfine fields for phase segregation, from which we conclude the transition between normal and SDW phases is discontinuous. A tricritical point (TCP) is identified. A crossover to FL behavior identified by spin-lattice relaxation measurements intersects the normal to SDW phase boundary very close to the TCP.