Geometry induced net spin polarization of -wave altermagnets
Phys. Rev. Materials 10, 044406 – Published 23 April, 2026
DOI: https://doi.org/10.1103/8ntv-rwyn
Abstract
Altermagnets exhibit spin-split electronic band structures despite having zero net magnetization, making them attractive for field-free spintronic applications. In this work, we show that a finite rectangular altermagnetic sample can acquire a net spin polarization purely because of its geometry. This effect arises from the interplay between the anisotropic, spin-resolved Fermi contours of an altermagnet, the discrete sampling of momentum space and unequal sample dimensions. By explicitly counting occupied states, we demonstrate that rectangular samples with host a finite spin polarization, which vanishes in the symmetric limit and in the thermodynamic limit. We further show that this geometry-induced spin polarization can be directly probed in transport measurements. In the tunneling regime, the charge and the spin conductances exhibit characteristic patterns as a function of sample dimensions, faithfully reflecting the underlying spin polarization. In addition, transport across ferromagnet–altermagnet–ferromagnet junctions reveals an asymmetric magnetoresistance with respect to reversal of the Zeeman field, providing an independent transport signature of the finite spin polarization. Our results establish geometry as an effective control parameter for spin polarization in altermagnets and suggest a viable route for exploiting finite-size effects in mesoscopic altermagnetic spintronic devices.
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This article appears in the following collection:
Altermagnetic and Related Materials
Editors of Physical Review Materials are pleased to present the Collection on Altermagnetic and Related Materials, highlighting cutting-edge advances in theoretical and experimental identification of novel altermagnetic materials, their properties, and their potential applications. The Collection is being guest-edited by Kirill Belashchenko of the University of Nebraska-Lincoln (USA), Cheng Song of Tsinghua University (China), and Peter Wadley of The University of Nottingham (UK). Every article published in this collection underwent a rigorous peer review process, adhering to the same high standards applied to all papers. The Physical Review Materials editorial team managed the peer review and made all editorial decisions.
