An antisite defect mechanism for room temperature ferroelectricity in orthoferrites

Shuai Ning; Abinash Kumar; Konstantin Klyukin; Eunsoo Cho; Jong Heon Kim; Tingyu Su; Hyun-Suk Kim; James M LeBeau; Bilge Yildiz; Caroline A Ross

doi:10.1038/s41467-021-24592-w

An antisite defect mechanism for room temperature ferroelectricity in orthoferrites

Nat Commun. 2021 Jul 14;12(1):4298. doi: 10.1038/s41467-021-24592-w.

Authors

Shuai Ning^{1

2}, Abinash Kumar³, Konstantin Klyukin³, Eunsoo Cho³, Jong Heon Kim⁴, Tingyu Su³, Hyun-Suk Kim⁴, James M LeBeau³, Bilge Yildiz^{3

5}, Caroline A Ross⁶

Affiliations

¹ Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. sning@nankai.edu.cn.
² School of Materials Science and Engineering, National Institute for Advanced Materials, Nankai University, Tianjin, People's Republic of China. sning@nankai.edu.cn.
³ Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
⁴ Department of Materials Science and Engineering, Chungnam National University, Daejeon, Korea.
⁵ Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
⁶ Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. caross@mit.edu.

Abstract

Single-phase multiferroic materials that allow the coexistence of ferroelectric and magnetic ordering above room temperature are highly desirable, motivating an ongoing search for mechanisms for unconventional ferroelectricity in magnetic oxides. Here, we report an antisite defect mechanism for room temperature ferroelectricity in epitaxial thin films of yttrium orthoferrite, YFeO₃, a perovskite-structured canted antiferromagnet. A combination of piezoresponse force microscopy, atomically resolved elemental mapping with aberration corrected scanning transmission electron microscopy and density functional theory calculations reveals that the presence of Y_Fe antisite defects facilitates a non-centrosymmetric distortion promoting ferroelectricity. This mechanism is predicted to work analogously for other rare earth orthoferrites, with a dependence of the polarization on the radius of the rare earth cation. Our work uncovers the distinctive role of antisite defects in providing a mechanism for ferroelectricity in a range of magnetic orthoferrites and further augments the functionality of this family of complex oxides for multiferroic applications.