Evidence of a New Current-Induced Magnetoelectric Effect in a Toroidal Magnetic Ordered State of UNi4B

Magnetization measurements under direct electric current were performed in a toroidal magnetic ordered state of UNi4B to test a recent theoretical prediction of current-induced magnetization in a metallic system lacking local-inversion symmetry. We found that electric current parallel to [2110] and [0001] in the hexagonal 4-index notation induces a uniform magnetization along the [0110] direction. The observed behavior of the induced magnetization is essentially consistent with the theoretical prediction; however, it also shows an inconsistency suggesting that the antiferromagnetic state of UNi4B could not be simply regarded as a uniform toroidal order in the ideal honeycomb layered structure.