J. Phys. IV France 12 (2002) Pr9-389
High magnetic field NMR investigation of the spin density wave phase of TMTSF 2PF 6W.G. Clark1, F. Zamborsky1, B. Alavi1, P. Vonlanthen1, W. Moulton2, P. Kuhns2 and A. Reyes2
1 UCLA Physics and Astronomy, Los Angeles, U.S.A.
2 National High Magnetic Field Laboratory, Tallahassee, FL, U.S.A.
We report proton NMR measurements of the effect of very high magnetic fields up to 44.7 T (1.9 GHz) on the spin density wave (SDW) transition of the organic conductor TMTSF 2PF 6. Up to 1.8 GHz, no effect of critical slowing close to the transition is seen on the proton relaxation rate (1/T 1), which is determined by the SDW fluctuations associated with the phase transition at the NMR frequency. Thus, the correlation time for such fluctuations is less than 1O-10s. A possible explanation for the absence of longer correlation times is that the transition is weakly first order, so that the full critical divergence is never achieved. The measurements also show a dependence of the transition temperature on the orientation of the magnetic field and a quadratic dependence on its magnitude that agrees with earlier transport measurements at lower fields. The UCLA part of this work was supported by NSF Grant DMR-0072524.
© EDP Sciences 2002