Room-Temperature Polar Ferromagnet ScFeO3 Transformed from a High-Pressure Orthorhombic Perovskite Phase

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• 作者：Takahiro Kawamoto ; Koji Fujita ; Ikuya Yamada ; Tomohiko Matoba ; Sung Joo Kim ; Peng Gao ; Xiaoqing Pan ; Scott D. Findlay ; C茅dric Tassel ; Hiroshi Kageyama ; Andrew J. Studer ; James Hester ; Tetsuo Irifune ; Hirofumi Akamatsu ; Katsuhisa Tanaka
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：October 29, 2014
• 年：2014
• 卷：136
• 期：43
• 页码：15291-15299
• 全文大小：561K
• ISSN：1520-5126

文摘

Multiferroic materials have been the subject of intense study, but it remains a great challenge to synthesize those presenting both magnetic and ferroelectric polarizations at room temperature. In this work, we have successfully obtained LiNbO₃-type ScFeO₃, a metastable phase converted from the orthorhombic perovskite formed under 15 GPa at elevated temperatures. A combined structure analysis by synchrotron X-ray and neutron powder diffraction and high-angle annular dark-field scanning transmission electron microscopy imaging reveals that this compound adopts the polar R3c symmetry with a fully ordered arrangement of trivalent Sc and Fe ions, forming highly distorted ScO₆ and FeO₆ octahedra. The calculated spontaneous polarization along the hexagonal c-axis is as large as 100 渭C/cm². The magnetic studies show that LiNbO₃-type ScFeO₃ is a weak ferromagnet with T_N = 545 K due to a canted G-type antiferromagnetic ordering of Fe³⁺ spins, representing the first example of LiNbO₃-type oxides with magnetic ordering far above room temperature. A comparison of the present compound and rare-earth orthorhombic perovskites RFeO₃ (R = La鈥揕u and Y), all of which possess the corner-shared FeO₆ octahedral network, allows us to find a correlation between T_N and the Fe鈥揙鈥揊e bond angle, indicating that the A-site cation-size-dependent octahedral tilting dominates the magnetic transition through the Fe鈥揙鈥揊e superexchange interaction. This work provides a general and versatile strategy to create materials in which ferroelectricity and ferromagnetism coexist at high temperatures.