Stratonovich-Ito integration scheme in ultrafast spin caloritronics

The magnonic spin Seebeck effect is a key element of spin caloritronics, a field that exploits thermal effects for spintronic applications. Early studies were focused on investigating the steady-state nonequilibrium magnonic spin Seebeck current, and the underlying physics of the magnonic spin Seebeck effect is now relatively well established. However, the initial steps of the formation of the spin Seebeck current are in the scope of recent interest. To address this dynamical aspect theoretically, we propose here an alternative approach to the time-resolved spin Seebeck effect. Our method exploits the supersymmetric theory of stochastics and the Stratonovich-Ito integration scheme. We found that in the early step the spin Seebeck current has both nonzero transversal and longitudinal components. As the magnetization dynamics approaches the steady state, the transversal components decay through dephasing over the dipole-dipole reservoir. The timescale for this process is typically in subnanoseconds, pointing thus to the potential of an ultrafast control of the dynamical spin Seebeck during its buildup.