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arXiv · 1606.03170

Octahedral rotation patterns in strained EuFeO3 and other Pbnm perovskite films: Implications for hybrid improper ferroelectricity

A. K. Choquette·C. R. Smith·R. J. Sichel-Tissot·E. J. Moon·M. D. Scafetta·E. Di Gennaro·F. Miletto Granozio·E. Karapetrova·S. J. May
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Abstract

We report the relationship between epitaxial strain and the crystallographic orientation of the in-phase rotation axis and A-site displacements in Pbnm-type perovskite films. Synchrotron diffraction measurements of EuFeO3 films under strain states ranging from 2% compressive to 0.9% tensile on cubic or rhombohedral substrates exhibit a combination of a-a+c- and a+a-c- rotational patterns. We compare the EuFeO3 behavior with previously reported experimental and theoretical work on strained Pbnm-type films on non-orthorhombic substrates, as well as additional measurements from LaGaO3, LaFeO3, and Eu0.7Sr0.3MnO3 films on SrTiO3. Compiling the results from various material systems reveals a general strain dependence in which compressive strain strongly favors a-a+c- and a+a-c- rotation patterns and tensile strain weakly favors a-a-c+ structures. In contrast, EuFeO3 films grown on Pbnm-type GdScO3 under 2.3% tensile strain take on a uniform a-a+c- rotation pattern imprinted from the substrate, despite strain energy considerations that favor the a-a-c+ pattern. These results point to the use of substrate imprinting as a more robust route than strain for tuning the crystallographic orientations of the octahedral rotations and A-site displacements needed to realize rotation-induced hybrid improper ferroelectricity in oxide heterostructures.

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A. K. Choquette, C. R. Smith, R. J. Sichel-Tissot, E. J. Moon, M. D. Scafetta, E. Di Gennaro, F. Miletto Granozio, E. Karapetrova, S. J. May. 2016-06-10. Octahedral rotation patterns in strained EuFeO3 and other Pbnm perovskite films: Implications for hybrid improper ferroelectricity. https://doi.org/10.1103/physrevb.94.024105

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