Antiferromagnetism and spin reorientation in "PbCrO3".

The perovskite "PbCrO(3)" was synthesized at high pressure and high temperature. Its magnetic properties have been investigated by means of magnetization, specific heat, and resistivity measurements. Earlier workers had concluded it to have a G-type antiferromagnetic structure. However, our measurements suggest a rather more complex situation: first, a weak ferromagnetic transition of the Cr(IV) spins occurs at 245 K; this is followed by a temperature-driven spin reorientation starting at 185 K and ending at 62 K. Since zero-magnetic-field spin reorientation in the "PbCrO(3)" perovskite should not be expected, an intrinsic "magnetoelectric effect", associated with the lone-pair Pb electrons, seems to be responsible for the observed smooth rotation of the Cr-spins.