High-Temperature Ferrimagnetism with Large Coercivity and Exchange Bias in the Partially Ordered 3d/5d Hexagonal Perovskite Ba2Fe1.12Os0.88O6

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• 作者：Hai L. FengPeter Adler ; Manfred Reehuis ; Walter Schnelle ; Philip Pattison ; Andreas Hoser ; Claudia Felser ; Martin Jansen
• 刊名：Chemistry of Materials
• 出版年：2017
• 出版时间：January 24, 2017
• 年：2017
• 卷：29
• 期：2
• 页码：886-895
• 全文大小：524K
• ISSN：1520-5002

文摘

Double perovskite oxides A₂BB′O₆ combining 3d and 4d or 5d transition metal ions at the B and B′ sites feature a variety of magnetic and magneto-electric properties. Targeting Ba₂FeOsO₆, we synthesized powder samples of nonstoichiometric Ba₂Fe_1.12Os_0.88O₆ by solid-state reaction from the oxides. The crystal structure was investigated by using synchrotron powder X-ray and powder neutron diffraction. In contrast to Ca₂FeOsO₆ and Sr₂FeOsO₆, the compound adopts the hexagonal 6L perovskite structure (space group P3̅m1) with partial Fe–Os order at both the face-sharing B₂O₉ dimer and the corner sharing BO₆ transition metal sites. Magnetization, neutron diffraction, and ⁵⁷Fe Mössbauer spectroscopy results show that Ba₂Fe_1.12Os_0.88O₆ develops ferrimagnetic order well above room temperature at T_C ≈ 370 K. The nonsaturated magnetization curve at 2 K features a magnetic moment of 0.4 μ_B per formula unit at 7 T and a pronounced hysteresis with a coercive field of about 2 T. Large exchange bias effects are observed when the magnetization curves are measured after field cooling. The peculiar magnetic properties of Ba₂Fe_1.12Os_0.88O₆ are attributed to an inhomogeneous magnetic state formed as a consequence of the atomic disorder. Our results indicate that hexagonal double-perovskite-related oxides are a promising class of compounds for finding new materials with potential applications as hard magnets or in the area of spintronics.