Photoinduced magnetic phase transitions in the cubic Kondo-lattice model
Abstract
We theoretically study photoinduced magnetic phase transitions and their dynamical processes in the Kondo-lattice model on a cubic lattice. It is demonstrated that light irradiation gives rise to magnetic phase transitions from the ground-state ferromagnetic state to a three-dimensional antiferromagnetic state as a nonequilibrium steady state in the photodriven system. This phase transition occurs as a consequence of the formation of pseudo half-filling band occupation via the photoexcitation and relaxation of electrons, where all the electron states constituting the lower band separated from the upper band by an exchange gap are partially but nearly uniformly occupied. We also find that several types of antiferromagnetic correlations, e.g., A-type and C-type antiferromagnetic correlations, appear in a transient state of the dynamical phase transition. By calculating magnon spectra for the photodriven system, we argue that the instability to the A-type or C-type antiferromagnetic state occurs in the ferromagnetic ground state as a softening of the magnon band dispersion at corresponding momentum points depending on the light polarization. Our findings provide important insights into the understanding of photoinduced magnetic phase transitions in the three-dimensional Kondo-lattice magnets.