Room-Temperature Multiferroic New Candidates in Hexagonal RFeO3

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Abstract
08-004 Xiang Ming Chen Chen, X.(Zhejiang University); Liu, J.(Zhejiang University); Sun, T.(Zhejiang University); Liu, X.(Zhejiang University); Tian, H.(Zhejiang University); Gao, T.(Zhejiang University); Exploring single phase multiferroic material has been a long-time-sought quest due to the promise of novel spintronic devices. Recently, the hexagonal rare earth ferrites h-RFeO3(R=rare earth element) have attracted the increasing scientific interests as room-temperature multiferroic new candidates. However, the centrosymmetric orthorhombic structure is generally stable for most RFeO3 at room-temperature, while the hexagonal phase is only stable under some strict conditions. Therefore, it is the key issue to tune the symmetry of RFeO3 into hexagonal for creating room-temperature multiferroic new materials. Another important issue for h-RFeO3 multiferroic ceramics is the evaluation of room temperature ferroelectricity due to the semiconductor nature. In the present work, h-RFeO3 multiferroic ceramics are designed and created by introducing chemical pressure (In-substitution for Lu) in LuFeO3. The crystal structure of the present ceramics is tuned from centrosymmetric Pbnm (x=0) to non-centrosymmetric P63cm (x=0.4~0.6), and subsequently to centrosymmetricP63/mmc (x=0.75), while the Pbnm and P63cm biphase structure is detected for x=0.25. The Curie temperature for the polar P63cm (x=0.4~0.6) phase is much higher than room temperature, and the ferroelectric domains at atomic scale has been evaluated by the aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HADDF STEM), where the spontaneous polarization of 1.73?C/cm2 is determined x=0.5. Meanwhile, two magnetic transitions have been determined for all compositions, that is paramagnetic to antiferromagnetic transition at Néel temperature TN (~350K for x=0.4~0.6), and antiferromagnetic to weak-ferromagnetic transition at spin-reorientation temperature TSR. Hence, the co-presence of ferroelectric and antiferromagnetic orders confirms the present hexagonal Lu1-xInxFeO3 ceramics as the promising room temperature multiferroic materials.
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