Features of the magnetoelectric properties of BiFeO3 in high magnetic fields

It is shown that the destruction of the cycloidal structure of the magnetic ferroelectric BiFeO3 by a high magnetic field (H(n)approximate to 200 kOe) leads to the onset of a linear magnetoelectric effect and the appearance o f a toroidal moment. The proof of the existence of a toroidal moment T in a high magnetic field (H >H-n) is based on the experimental observation that the off-diagonal components of the linear ME effect tensor are asymmetric (alpha (12)=-alpha (21) for L parallel toc, where L is the antiferromagneti c vector), inasmuch as T(z)similar to alpha (12)-alpha (21). (C) 2001 Ameri can Institute of Physics.