Floquet-driven Interlayer Spin Pumping in Transition Metal Dichalcogenide Heterostructures*

Spin pumping through the magnetization precession of a ferromagnet is one of the common techniques used for generating and manipulating spin currents, which is central to the implementation of spintronic devices. Using the Floquet Green's function formalism for systems driven by a time-periodic potential, we study the pumped spin current driven by the magnetization precession of a ferromagnetic layer. We consider a vertical heterostructure comprising a transition metal dichalcogenide (TMD) layer and two-dimensional electron gas separated by an insulating spacer, with the TMD layer coupled to the ferromagnetic layer through exchange coupling. A non-perturbative formulation of the tunneling spin current is developed within the Floquet-Keldysh formalism, from which we have analyzed the dependence of the tunneling spin current on the precession angle, the driving frequency, and the exchange coupling strength. Our theory of spin pumping from TMD materials allows the optimization of pumped spin currents by exploring experimentally available materials parameter space for TMDs and the two-dimensional electron gas.