摘要
Measurements of resonant soft x-ray magnetic scattering reveal anomalous ordering of 3d spins and 2p holes in perovskite La 1/3 Sr 2/3 FeO 3 , which is known to exhibit three-dimensional (3D) charge and spin ordering along the [111] direction. Upon cooling, a quasi-two-dimensional phase consisting of ferromagnetic and charge- disproportionated (111) trilayers of Fe3 + -Fe5 + -Fe 3+ precedes the development of 3D magnetic ordering at the transition temperature, in sharp contrast to an ordinary transition from the paramagnetic and charge-uniform phase to the antiferromagnetic and charge-disproportionated phase expected according to conventional wisdom. © 2010 The American Physical Society.