Seminars Archive

Resonant X-ray Scattering as a Direct Probe of Orbital Order in V2O3

Abstract
V2O3 is a paramagnetic metal at room temperature; at 150 K it undergoes a Mott transition to an insulating phase, accompanied by a peculiar antiferromagnetic transition. Twenty years ago, Castellani, Natoli and Ranninger speculated that it is also accompanied by a transition to an ordered pattern in the occupation of degenerate V 3d orbitals. Experimental evidence for this "orbital order" was however very indirect until recently. Fabrizio, Altarelli and Benfatto recently suggested that resonant X-ray scattering at the Vanadium K-edge can provide a definite direct observation of this elusive order parameter. Very recently, experiments carried out by Paolasini et al. at the Magnetic Scattering Beamline of ESRF showed that this is indeed the case, confirmed Castellani et al.`s predictions, and established the wave vector and other features of the orbital order parameter.