Thermodynamic, transport and magnetic properties of -NaV2O5
Institut für Physik, Universität Augsburg - D-86135 Augsburg, Germany
Accepted: 21 April 1998
We report on heat capacity, electrical resistance and high-temperature ESR experiments on the spin-Peierls compound -. The spin susceptibility at high temperatures () closely follows a Bonner-Fisher behavior with an exchange interaction but differs significantly from this predictions at lower temperatures. The temperature dependence of the heat capacity can be explained assuming a sum of a linear (magnetic) and a Debye (lattice) contribution. The specific-heat jump at cannot be described by the opening of a gap in mean-field approximation. The release of entropy is almost by a factor of 20 too high compared to the MF predictions of the Bonner-Fisher model for a uniform AFM spin chain with an exchange interaction of . The electrical resistance R(T) can roughly be described by variable-range hopping processes and a large anomaly at the transition into the low-temperature dimerized state. From these observations we conclude that the phase transition in - at 35 K cannot be explained by a spin-Peierls transition alone.
PACS: 71.30.+h – Metal-insulator transitions and other electronic transitions / 72.20.-i – Conductivity phenomena in semiconductors and insulators / 76.30.-v – Electron paramagnetic resonance and relaxation
© EDP Sciences, 1998