Experimental evidence of anapolar moments in the antiferromagnetic insulating phase of V2O3 obtained from x-ray resonant Bragg diffraction

We have investigated the antiferromagnetic insulating phase of the Mott-Hubbard insulator vanadium sesquioxide (V2O3) by resonant x-ray Bragg diffraction at the vanadium K edge. Combining the information obtained from azimuthal angle scans, linear incoming polarization scans and by fitting collected data to the scattering amplitude derived from the established chemical I2/a and magnetic space groups we provide direct experimental evidence of the ordering motif of vanadium magnetoelectric multipoles in V2O3. Experimental data (azimuthal dependence and polarization analysis) collected at space-group forbidden Bragg reflections are successfully accounted within our model in terms of vanadium magnetoelectric multipoles. We demonstrate that resonant x-ray diffraction intensities in all space-group forbidden Bragg reflections of the kind (hkl)(m) with odd h are produced by an E1-E2 event. The determined multipolar parameters offer a test for ab initio calculations in this material, which can lead to a deeper and more quantitative understanding of the physical properties of V2O3.