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arXiv · 2101.08645

Finite temperature fluctuation-induced order and responses in magnetic topological insulators

Marius Scholten·Jorge I. Facio·Rajyavardhan Ray·Ilya M. Eremin·Jeroen van den Brink·Flavio S. Nogueira
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Abstract

We derive an effective field theory model for magnetic topological insulators and predict that a magnetic electronic gap persists on the surface for temperatures above the ordering temperature of the bulk. Our analysis also applies to interfaces of heterostructures consisting of a ferromagnetic and a topological insulator. In order to make quantitative predictions for MnBi$_2$Te$_4$, and for EuS-Bi$_2$Se$_3$ heterostructures, we combine the effective field theory method with density functional theory and Monte Carlo simulations. For MnBi$_2$Te$_4$ we predict an upwards Néel temperature shift at the surface up to $15 \%$, while the EuS-Bi$_2$Se$_3$ interface exhibits a smaller relative shift. The effective theory also predicts induced Dzyaloshinskii-Moriya interactions and a topological magnetoelectric effect, both of which feature a finite temperature and chemical potential dependence.

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Marius Scholten, Jorge I. Facio, Rajyavardhan Ray, Ilya M. Eremin, Jeroen van den Brink, Flavio S. Nogueira. 2021-07-13. Finite temperature fluctuation-induced order and responses in magnetic topological insulators. https://doi.org/10.1103/physrevresearch.3.l032014

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