Structural dichroism in the antiferromagnetic insulating phase of V_2O_3

We performed near-edge x-ray absorption spectroscopy at the V K edge in the antiferromagnetic insulating (AFI) phase of a 2.8% Cr-doped V2O3 single crystal. Linear dichroism of several percent is measured in the hexagonal plane and found to be in good agreement with ab initio calculations based on multiple scattering theory. This experiment definitively proves the structural origin of the signal and therefore solves a controversy raised by previous interpretations of the same dichroism as nonreciprocal. It also calls for a further investigation of the role of the magnetoelectric annealing procedure in cooling to the AFI phase