Floquet engineering of magnetism in topological insulator thin films

Abstract Dynamic manipulation of magnetism in topological materials is demonstrated here via a Floquet engineering approach using circularly polarized light. Increasing the strength laser field, besides expected phase transition (PT), magnetically doped insulator thin film also undergoes magnetic PT from ferromagnetism to paramagnetism, whose critical behavior strongly depends on quantum quenching. In sharp contrast equilibrium case, non-equilibrium Curie temperatures vary for different time scale and experimental setup, not all relying change topology. Our discoveries deepen understanding relationship between topology regime extend optoelectronic device applications materials.