Altermagnets, a newly discovered class of materials, exhibit zero net magnetization while hosting spin-split electronic bands. However, monolayer altermagnets maintain degenerate band gaps at the high-symmetry X and Y points in the Brillouin zone, manifesting a paravalley phase characterized by unpolarized valley states. In this work, we demonstrate that spontaneously broken valley degeneracy can be achieved through interlayer sliding in engineered M2A2B and M2AA′B bilayer altermagnets by first-principles calculations and minimal microscopic model. We propose a promising route to achieve antiferromagnetic half-metal driven by sliding and emergent ferrovalley phase without applied electric field, which is realized in the V2SSeO engineered bilayer. Our calculations also reveal that Mo2O2O exhibits the largest valley splitting gap of ~0.31 eV, making it a promising candidate for valley-spin valve devices. Furthermore, band structure calculations on Mo2AA′O materials demonstrate that increasing the difference in atomic number (ΔZ) between A and A′ site atoms effectively enhances valley polarization. This work establishes a novel platform for discovering and controlling ferrovalley states in altermagnetic systems.
@article{arxiv.2509.00430,
title = {Sliding-induced ferrovalley polarization and possible antiferromagnetic half-metal in bilayer altermagnets},
author = {Xin Zhang and Shihao Zhang},
journal= {arXiv preprint arXiv:2509.00430},
year = {2026}
}