Evolution of magnetic correlation in the doped Hubbard model with altermagnetic spin splitting

The evolution of magnetic correlation in strongly correlated electron systems with altermagentic spin splitting remains largely unexplored. Here we investigate how spin splitting generated by spin-dependent next-nearest-neighbor hopping ′ reshapes the Fermi surface nesting and Van Hove singularities in the two-dimensional square-lattice Hubbard model, leading evolution of magnetic instabilities. Using the constrained-path quantum Monte Carlo method, we find the dominant magnetic correlation as functions of the filling and ′ by computing the momentum-resolved spin structure factor. The analysis reveals a transition from antiferromagnetic (, ) order in the isotropic, half filled system to noncollinear spiral (, ) order upon increasing the spin-dependent anisotropy or doping away from half filling, ultimately entering a short-range correlation regime where stripe and spiral correlation coexist. These findings highlight a possible route to realizing spiral correlation in altermagnetic systems, potentially providing a platform for spintronic devices that exploit noncollinear spin textures. ©2026 American Physical Society.