Neel-vector-orientation induced direction-robust spin filtering in two-dimensional altermagnets
Year: 2026
Type: article
Abstract: Whether an antiferromagnet can host direction-robust spin-polarized transport without a conventional spin-selective band gap remains a central challenge in antiferromagnetic spintronics. Here we establish a gapless, direction-robust spin-filtering mechanism in a compensated two-dimensional altermagnetic Weyl semimetal that requires neither a spin-selective band gap nor a large velocity contrast between spin projections. Using Janus monolayer Ta$_2$TeSeO as a realistic platform, we combine symmetry analysis with first-principles calculations, full-Brillouin-zone Wannier interpolation, and semiclassical transport. Rotating the Néel vector removes a unitary-mirror constraint and shifts one Weyl-cone pair away from its parent high-symmetry line. For an in-plane Néel vector, the residual $C_{2z}\mathcal T$ symmetry forbids the independent $σ_y$ mass that would open a local gap, allowing the reconstructed cones to shift in momentum while remaining gapless. Breaking unitary $C_{2z}$ simultaneously lifts the energy equivalence of the remaining mirror-pinned Weyl cones. The resulting coexistence of a metallic spin-projected manifold and a low-DOS Weyl-derived manifold produces a predominantly DOS-driven conductance imbalance. At charge neutrality and 20~K, the longitudinal conductivity polarization for $\mathbf n\parallel x$ remains positive for every in-plane current direction and ranges from $76.4\%$ to $82.0\%$. The degenerate in-plane magnetic anisotropy facilitates reversible switching between symmetry-related spin-filtering states using strain or weak anisotropic fields. This Néel-vector-driven symmetry mechanism provides a general route to direction-robust gapless spin filtering in compensated altermagnets.
DOI: 10.1103/nyd5-ddcb
Authors: Xin Chen, Jin Zou, Lipeng Song, Wei Sun, Yiwen Wu, Luyao Zhu, Xu Cheng, Duo Wang, Biplab Sanyal
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: Department of Science and Technology, Ministry of Science and Technology, India, Swedish Foundation for International Cooperation in Research and Higher Education, Vetenskapsrådet, China Scholarship Council, Natural Science Foundation of Shandong Province, Scheme for Promotion of Academic and Research Collaboration, National Supercomputing Center, Korea Institute of Science and Technology Information
OpenAlex ID: W4415964959
FWCI:
Cites:
Cited by:
Related to: