Emergence of tunable exceptional points in altermagnet-ferromagnet junctions

Abstract

The existence of exceptional points (EPs) $-$ where both eigenvalues and eigenvectors converge $-$ is a key characteristic of non-Hermitian physics. A newly-discovered class of magnets $-$ termed as altermagnets (AMs) $-$ are characterized by a net zero magnetization as well as spin-split bands. In this study, we propose the emergence of non-Hermitian physics at AM-ferromagnet (FM) junctions. We discover that such a junction hosts tunable EPs. We demonstrate that the positions of these emergent EPs can be tuned using an external applied magnetic field and show that for a critical value of the applied magnetic field the EPs can annihilate. Notably, the number and position of the EPs crucially depends on the type of AM and its orientation with respect to the FM. Our work puts forth a promising platform of exploration of non-Hermitian physics in an emerging class of magnetic materials.

7 pages, 6 figures

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• Orientation dependent anomalous Hall and spin Hall currents at junctions of altermagnets with $p$-wave magnets
• Non-Hermitian higher-order topological insulators enabled by altermagnet engineering
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• Altermagnetism from the viewpoint of chemistry
• Floquet multiple exceptional points with higher-order skin effect
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