Effects of biaxial strain on the improper multiferroicity in h-LuFeO₃ films studied using the restrained thermal expansion method

Authors

Kishan Sinha, University of Nebraska - LincolnFollow
Yubo Zhang, Temple University
Xuanyuan Jiang, University of Nebraska - LincolnFollow
Hongwei Wang, Temple University
Xiao Wang, Bryn Mawr College
Xiaozhe Zhang, University of Nebraska-Lincoln
Philip J. Ryan, Argonne National Laboratory
Jong-Woo Kim, Argonne National Laboratory
John Bowlan, Los Alamos National Laboratory
Dmitry A. Yarotski, Los Alamos National Laboratory
Yuelin Li, Argonne National Laboratory
Anthony D. DiChiara, Argonne National Laboratory
Xuemei Cheng, Bryn Mawr College
Xifan Wu, Temple University
Xiaoshan Xu, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2017

Citation

PHYSICAL REVIEW B 95, 094110 (2017)

Comments

©2017 American Physical Society

Abstract

Elastic strain is potentially an important approach in tuning the properties of the improperly multiferroic hexagonal ferrites, the details of which, however, have been elusive due to experimental difficulties. Employing the method of restrained thermal expansion, we have studied the effect of isothermal biaxial strain in the basal plane of h-LuFeO₃ (001) films. The results indicate that a compressive biaxial strain significantly enhances the K₃ structural distortion (the order parameter of the improper ferroelectricity), and the effect is larger at higher temperatures. The compressive biaxial strain and the enhanced K₃ structural distortion together cause an increase in the electric polarization and a reduction in the canting of the weak ferromagnetic moments in h-LuFeO3, according to our first principles calculations. These findings are important for understanding the strain effect as well as the coupling between the lattice and the improper multiferroicity in h-LuFeO₃. The experimental elucidation of the strain effect in h-LuFeO₃ films also suggests that the restrained thermal expansion can be a viable method to unravel the strain effect in many other thin film materials.