Orbital state and magnetic properties of (formula presented)

Abstract

(formula presented) is one of the most puzzling compounds among transition metal oxides because of its heavy-fermion-like behavior at low temperatures. In this paper we present results for the orbital state and magnetic properties of (formula presented) obtained from a combination of density functional theory within the local density approximation and dynamical mean-field theory (DMFT). The DMFT equations are solved by quantum Monte Carlo simulations. The trigonal crystal field splits the V (formula presented) orbitals such that the (formula presented) and (formula presented) orbitals cross the Fermi level, with the former being slightly lower in energy and narrower in bandwidth. In this situation, the (formula presented) Coulomb interaction leads to an almost localization of one electron per V ion in the (formula presented) orbital, while the (formula presented) orbitals form relatively broad bands with 1/8 filling. The theoretical high-temperature paramagnetic susceptibility (formula presented) follows a Curie-Weiss law with an effective paramagnetic moment (formula presented) in agreement with the experimental results. © 2003 The American Physical Society.