Spin dynamics from the Niu-Kleinman adiabatic approach and slave-boson mean-field theory
Phys. Rev. B 114, 165144 – Published 30 September, 2026
DOI: https://doi.org/10.1103/3hcv-nckk
Abstract
Spin-wave excitations provide a central probe of magnetic order and electronic correlations in strongly correlated materials. In this work, we develop an adiabatic theory of spin dynamics by combining the Niu-Kleinman formalism with Kotliar-Ruckenstein slave-boson theory. For each frozen spin configuration, the constrained slave-boson saddle point is solved self-consistently, allowing the Berry-curvature matrix and energy Hessian entering the linearized adiabatic equations of motion to be extracted directly. Applied to the half-filled single-orbital Hubbard model, the resulting spin-wave dispersion shows substantially improved agreement with determinant quantum Monte Carlo benchmarks compared with the random phase approximation and closely approaches results from the time-dependent Gutzwiller approximation. We further extend the method to a two-orbital model of , demonstrating its applicability to realistic multiorbital correlated systems. Because the approach only requires saddle-point solutions near the magnetic ground state, it remains computationally efficient while incorporating strong correlation effects beyond conventional weak coupling descriptions, providing a practical framework for studying low-energy spin excitations in correlated quantum materials.