Sophie Weber^1*, Andrea Urru^2*, Nicola Spaldin^3*

1 Department of Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden

2 Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA

3 Materials Theory, ETH Zurich, 8093 Zurich, Switzerland

* Corresponding authors emails: sophie.weber@chalmers.se, au168@physics.rutgers.edu, nicola.spaldin@mat.ethz.ch

DOI10.24435/materialscloud:fz-1s [version v1]

Publication date: May 29, 2025

How to cite this record

Sophie Weber, Andrea Urru, Nicola Spaldin, Local magnetoelectric effects as predictors of surface magnetic order, Materials Cloud Archive 2025.89 (2025), https://doi.org/10.24435/materialscloud:fz-1s

Description

We use symmetry analysis and density functional theory to show that changes in magnetic order at a surface with respect to magnetic order in the bulk can be generically determined by considering local magnetoelectric responses of the crystal. Specifically, analysis of the atomic-site magnetoelectric responses, or equivalently the corresponding local magnetic multipoles, can be used to predict all surface magnetic modifications arising purely from symmetry lowering via termination of the bulk magnetic order. This analysis applies even in materials with no bulk magnetoelectric response or surface magnetization. We then demonstrate our arguments for two example antiferromagnets, metallic CuMnAs and rock-salt NiO. We find that the (010) and (1-10) surfaces of CuMnAs and NiO respectively exhibit a series of antiferroically, as well as roughness-sensitive, ferroically ordered, modifications of the surface magnetic dipole moments, via canting or changes in sublattice magnitude, consistent with the bulk ordering of the magnetic multipoles. Our findings demonstrate a universal bulk-boundary correspondance allowing the general prediction of minimal possible surface and interface magnetic modifications, even in non-magnetoelectric materials. Furthermore, it paves the way for more accurate interpretations of a wide variety of surface-sensitive measurements.

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Keywords

DFT Magnetism surface science symmetry analysis