14NNMR investigation of KSCN
J. Stefan Institute, SI-1000 Ljubljana, Slovenia
2 Institut für Experimentalphysik, Universität Wien A-1090, Wien, Austria
3 Department of Physics, University of Utah, Salt Lake City, Utah 84112
Accepted: 12 August 1997
We have directly determined with NMR the SCN head-tail flipping rate in KSCN on going through the order-disorder phase transition at Tc. The results can be explained in terms of an asymmetric double-well potential for the SCN reorientations below Tc and a symmetric double-well potential above Tc. The time scale for the SCN fluctuations is so slow that low symmetry angular rotation patterns are observed in the high-temperature high-symmetry phase. KSCN thus seems to be the first known example where a structural phase transition can be observed with NMR in the slow-motion and not in the fast-motion regime and where a dynamic breaking of the symmetry of the high-temperature phase takes place.
PACS: 64.70.Kb – Solid-solid transitions / 76.60.-k – Nuclear magnetic resonance and relaxation
© EDP Sciences, 1997