SUPPRESSION OF THE METAL-TO-INSULATOR TRANSITION IN BAVS3 WITH PRESSURE

The pressure dependence of the metal-to-insulator (MI) transition in BaVS3 has been studied up to applied hydrostatic pressures of 16 kbar. There is a substantial decrease in the transition temperature, with 14.8 kbar suppressing TMI from 69 K at ambient pressure to about 12 K. This behavior is discussed on the basis of the crystal structure of this quasi-one-dimensional compound. We argue that the ratio of the lattice constants parallel and perpendicular to the vanadium chains is the key parameter for understanding the pressure dependence of the MI transition. Thermal-expansion and magnetization measurements at ambient pressure show no additional phase transition below 69 K. Our results indicate that the metal-to-insulator transition may be a continuous isomorphic transition from the insulator with low susceptibility due to a gap in a band of extended states to a metal with a Curie-Weiss susceptibility due to correlations in the vanadium d band. © 1995 The American Physical Society.