Intrinsic antiferromagnetic half-metal and topological phases from the ferrovalley states of the sliding bilayer altermagnets

Abstract Altermagnetism is characterized by non-relativistic spin splitting and zero total magnetic moments. Herein, we identify intrinsic antiferromagnetic half-metallic phases and topological phases emerging from the ferrovalley states of sliding bilayer altermagnets. Taking the V ₂ OSSe system for example, first-principles calculations indicate that the spin-dependent interlayer hopping in the ferrovalley state ensures a direct gap in one valley (one spin channel) and band inversion in the other valley (opposite spin channel), which is manifested as an intrinsic antiferromagnetic half-metal. The microscopic model and effective Hamiltonian employed in this research confirm the universal spin-dependent interlayer hopping in the sliding altermagnet bilayer. Further calculations imply the existence of Chern insulators and gapless surface states in the sliding altermagnet bilayer. Adjusting the sliding direction can achieve the transition between different half-metals with conducting electrons of different spins, accompanied by the switching of gapless surface states of opposite spins. This work proposes a roadmap to achieve the intrinsic antiferromagnetic half-metals, laying the foundation for potential applications of intrinsic antiferromagnetic half-metals and topological phases in spintronics.