Low-Symmetry Monoclinic Phases and Polarization Rotation Path Mediated by Epitaxial Strain in Multiferroic BiFeO3 Thin Films
✍ Scribed by Zuhuang Chen; Zhenlin Luo; Chuanwei Huang; Yajun Qi; Ping Yang; Lu You; Chuansheng Hu; Tom Wu; Junling Wang; Chen Gao; Thirumany Sritharan; Lang Chen
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 863 KB
- Volume
- 21
- Category
- Article
- ISSN
- 1616-301X
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✦ Synopsis
Abstract
A morphotropic phase boundary driven by epitaxial strain has been observed in lead‐free multiferroic BiFeO~3~ thin films and the strain‐driven phase transitions have been widely reported as iso‐symmetric Cc‐Cc by recent works. In this paper, it is suggested that the tetragonal‐like BiFeO~3~ phase identified in epitaxial films on (001) LaAlO~3~ single crystal substrates is monoclinic M~C~. This M~C~ phase is different from the M~A~ type monoclinic phase reported in BiFeO~3~ films grown on low mismatch substrates, such as SrTiO~3~. This is confirmed not only by synchrotron X‐ray studies but also by piezoresponse force microscopy measurements. The polarization vectors of the tetragonal‐like phase lie in the (100) plane, not the (110) plane as previously reported. A phenomenological analysis is proposed to explain the formation of M~C~ Phase. Such a low‐symmetry M~C~ phase, with its linkage to M~A~ phase and the multiphase coexistence open an avenue for large piezoelectric response in BiFeO~3~ films and shed light on a complete understanding of possible polarization rotation paths and enhanced multiferroicity in BiFeO~3~ films mediated by epitaxial strain. This work may also aid the understanding of developing new lead‐free strain‐driven morphotropic phase boundary in other ferroic systems.