Thermodynamic, transport and magnetic properties of alpha '-NaV2O5

We report on heat capacity, electrical resistance and electron spin resonan ce experiments on alpha'-NaV2O5. At the phase transition temperature, the s pecific heat anomaly which can hardly be described within the framework of a spin-Peierls transition and a large anomaly in the electrical resistance reveal that the lattice degrees of freedom are strongly involved. ESR resul ts were obtained from 4 to 700 K. The spin susceptibility at high temperatu res closely follows a Bonner-Fisher behaviour, with an exchange constant of J = 578 K, but differs significantly from this theory at lower temperature s. (C) 1999 Elsevier Science B.V. All rights reserved.