Nonclassical spin dynamics, current pumping and the ensuing radiation in ultrfast-light-driven heterostructures of strongly correlated antiferromagnet NiO

Ultrafast light-induced spin and charge excitation and resulting magnetization dynamics are intensely studied in Ferromagnetic materials. However, the corresponding field for antiferromagnetic materials like NiO with strongly-correlated electrons is still in its infancy. In NiO, the long-range magnetic order vanishes, unless in the presence of extremely large anisotropy and a small magnetic field in one particular site. In such materials, the magnetic moments can no longer be treated classically with the Landau-Lifshitz-Gilbert (LLG) equation, or be treated with Ising approximation due to the presence of non-zero entanglement entropy. The ground state of antiferromagnetic material is highly entangled and deviates from the classical Neel state. Here we use multiscale quantum-classical formalism-where conduction electrons are described by the quantum mechanics, the incoming light is described by classical vector potential while outgoing electromagnetic radiation is computed using Jefimenko equations for retarded electric and magnetic fields. We apply this formalism to Mott insulator NiO with Rashba spin-orbit coupling to simulate proximity effects of a heavy metal like Pt to compute the time-dependent magnetization and entanglement of the system and from the pumped charge currents we compute the ensuing THz radiation.