Berlin 2024 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 9: KFM Poster Session

KFM 9.35: Poster

Monday, March 18, 2024, 18:00–20:00, Poster E

DFT study of local ferroic properties at twin walls in ferroelastic CaMnO₃ — •Ida Cathrine Skogvoll and Sverre Magnus Selbach — Department of Materials Science and Engineering, NTNU - Norwegian University of Science and Technology, NO-7491 Trondheim, Norway

Ferroic domain walls display compelling properties for nanoscale device applications, where suppression of the primary order parameter and local symmetry-breaking can give rise to phenomena absent in the bulk. In ferroelastic materials, twin walls exhibit breaking of inversion symmetry which can activate polar instabilities, yielding a local polarization. CaMnO₃ with space group Pnma, is a nonpolar antiferromagnetic material with strong spin-phonon coupling. This implies that antiferrodistortive distortions couple strongly to the magnetic structure, and that the strain field across a ferroelastic twin wall can modify local magnetic properties. It is thus a candidate material for realizing multiferroicity in a single-phase material. In this work, DFT + U calculations were carried out on ferroelastic domain walls in CaMnO₃, implementing different patterns of intra-plane and inter-plane magnetic orders, to conduct an investigation of the local magnetic properties along with the induced ion displacements. We find that the polarization profile at the wall is dependent on the type of magnetic order, as well as the local environment of octahedral distortions. Furthermore, the magnetic wall preferentially resides at the twin wall as opposed to the bulk. Finally, we discuss the emerging prospects of realizing room-temperature multiferroicity in ferroelastic domain walls.

Keywords: Multiferroic; Domain walls; Ferroic; Ferroelastic; Magnetism