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MA: Fachverband Magnetismus

MA 11: Functional Antiferromagnetism

MA 11.12: Talk

Monday, March 18, 2024, 18:00–18:15, EB 202

Surface-symmetry-driven phenomena in magnetoelectric Cr₂O₃ — •Oleksandr V. Pylypovskyi^1,2, Sophie F. Weber³, Pavlo Makushko¹, Igor Veremchuk¹, Nicola A. Spaldin³, and Denys Makarov¹ — ¹Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, 01328 Dresden, Germany — ²Kyiv Academic University, 03142 Kyiv, Ukraine — ³Materials Theory, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland

Antiferromagnetic (AFM) Cr₂O₃ is a unique collinear magnetoelectric material at room temperature. The bulk properties stemming from its magnetic symmetry render chromia of high interest for fundamentals and applications [1]. Features of the chromia surface remain much less explored. Here, we consider nominally compensated surfaces (m and a planes) of Cr₂O₃ [2]. We show that they provide a sizeable Dzyaloshinskii–Moriya interaction (DMI) determined by the surface magnetic symmetry point group and quantify it to be about 1 mJ/m² by means of ab initio and micromagnetic approaches. The DMI leads to the development of nonzero surface magnetization M^→ whose sign is uniquely determined by the AFM state. The m and a planes of Cr₂O₃ behave as the canted ferrimagnet and canted 4-sublattice antiferromagnet, respectively. The coupling of M^→ to the direction of the Néel vector is shown by magnetotransport measurements.

[1] P. Makushko et al., Nat. Comm. 13, 6745 (2022). [2] O.V. Pylypovskyi, S. F. Weber et al., ArXiv:2310.13438 (2023).

Keywords: Antiferromagnetism; Dzyaloshinksii-Moriya interaction; surface; weak ferromagnetism; spin canting