Spin Phenomena at Antiferromagnetic and Altermagnetic Interfaces

Lateral interfaces between distinct magnetic orders offer a promising route for uncovering new forms of interfacial exchange coupling and spin transport phenomena. While vertical heterostructures combining ferromagnets (FMs) and antiferromagnets (AFMs) have been widely explored in the context of exchange bias, spin-current transfer, and interfacial anisotropy [1–3], comparatively little attention has been given to lateral geometries, where magnetic order varies in-plane and interfacial coupling is mediated by distinct boundary conditions . The recent identification of altermagnets (AMs), collinear compensated magnets that exhibit spin-split band structures despite zero net magnetization [4,5], introduces a new dimension to this problem. In this work, we comparatively examine lateral interfaces formed between FMs, AFMs, and AMs, including representative configurations such as FM/AFM, FM/AM, and AM/AFM, to explore how variations in magnetic properties influence interfacial coupling, spin-wave transmission, and related phenomena. Building on established theoretical frameworks for FM/AFM coupling [6,7] and emerging models of altermagnetic spin polarization [4,5], we analyze how the lateral interface modifies boundary conditions and symmetry constraints relative to conventional layered systems. By positioning this investigation within the broader literature on interfacial magnetism and spin transport, we aim to clarify how combining FM, AFM, and AM orders in planar junctions can yield new coupling regimes and provide symmetry-driven design principles for future spintronic devices.

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