Altermagnets, a novel class of collinear magnetic materials, exhibit unique spin-split band structures, yet topological insulating states in intrinsic altermagnetic systems are rare. Here, we identify monolayer Fe2X2O (X = Cl, Br, I) as a new family of 2D altermagnetic real Chern insulators. These materials display robust d-wave altermagnetic ordering, semiconducting band gaps, and nontrivial real Chern numbers per spin channel, yielding spin-polarized topological corner modes. They also feature spin-polarized valleys with strong altermagnetism-valley-spin-lattice coupling, enabling valley-selective excitation via linear dichroism and strain-induced valley polarization. In multiferroic Fe2Cl2O, magnetism coexists with ferroelasticity, and an applied strain can switch the N\'eel vector. These findings position 2D iron oxyhalides as a promising platform for exploring altermagnetism and magnetic topological states for spintronics and valleytronics.
@article{arxiv.2510.12748,
title = {Two-Dimensional Altermagnetic Iron Oxyhalides: Real Chern Topology and Valley-Spin-Lattice Coupling},
author = {Yong-Kun Wang and Si Li and Shengyuan A. Yang},
journal= {arXiv preprint arXiv:2510.12748},
year = {2026}
}