B-site-disordered perovskite CaFe0.5Mn0.5O3 with unusually high valence Fe4+ was synthesized using a high-pressure technique. Fe4+ randomly distributed at half of the B sites shows charge disproportionation to Fe3+ and Fe5+. The spins of Fe3+,Fe5+, and Mn4+ order below 90 K. Analysis of low-temperature neutron powder-diffraction data revealed a G-type antiferromagnetic structure - where all the nearest-neighboring spins of Fe3+,Fe5+, and Mn4+ couple antiparallel - and the small ordered moment of 0.58μB reveals local charge ordering that gives rise to predominant Fe3+-O-Fe5+ antiferromagnetic arrangements. Despite the identical chemical compositions of CaFe0.5Mn0.5O3 and Ca2FeMnO6, the magnetic structure of the present CaFe0.5Mn0.5O3 is very different from the noncollinear one of layered B-site-ordered Ca2FeMnO6.
|Journal||Physical review B: Condensed matter and materials physics|
|Early online date||26 Sep 2016|
|Publication status||E-pub ahead of print - 26 Sep 2016|