Magnetic Structure and Electronic Study of Complex Oxygen-Deficient Manganites
,
María Hernando,
Marı́a Hernando,
M. Luisa Ruiz González,
M. Luisa Ruiz-González ,
Eva Céspedes,
Carlos Prieto ,
José M. Alonso,
Antonio Vallet-Reg\,́ Maŕ ́and Hernando,
Antonio Hernando ,
José M. González Calbet
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Abstract
Neutron diffraction and X-ray absorption near-edge structure (XANES) studies have been performed in La0.5Ca0.5MnO2.5, La0.5Sr0.5MnO2.5 and Nd0.5Sr0.5MnO2.5 oxygen-deficient perovskite compounds obtained by topotactic reduction. They all exhibit a brownmillerite structure with G-type antiferromagnetic ordering. Mn2+, Mn3+ and Mn4+ coexist at the octahedral sites, whereas only Mn2+ is placed in the tetrahedral positions. A magnetic moment of 1.6 microB has been detected at the tetrahedral layers, which can be explained by assuming Mn2+ is in a low-spin configuration.