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

Abstract: 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 $t'$ 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 $t'/t$ by computing the momentum-resolved spin structure factor. The analysis reveals a transition from antiferromagnetic $(π,π)$ order in the isotropic, half-filled system to non-collinear spiral $(π,q)$ 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 non-collinear spin textures.