External quadrupole magnetic field of antiferromagnetic Cr2O3

Abstract

We report the results of an experimental study of the external magnetic field of an antiferromagnetic Cr2O3 single-crystal. They confirm reliably that this field corresponds to a magnetic quadrupole field, as predicted by Dzyaloshinskii [Solid State Comm. 82, 570 (1992)] and observed by D. N. Astrov and N. B. Ermakov [JETP Lett. 59, 297 (1994)]. The quadrupole moment of the sample was found to be several times smaller than the value predicted by calculations.