Thermal boundary conductance across Co/Cu interfaces with spin-lattice interactions

Abstract

This work combines first-principles calculations, spin-lattice dynamics, and the non-equilibrium Green's function (NEGF) method to compute thermal boundary conductance at a three-dimensional Co-Cu interface, considering spin-lattice interactions. Spin-lattice interactions are quantified through exchange interactions between spins, and the exchange constants are obtained from first-principles calculations. Equilibrium molecular dynamics is used to calculate the heat flux across the interface after the spin and lattice subsystems are in equilibrium. Because of the weak interaction between Co and Cu layers adjacent to the interface, spin-wave transmission is low. Spins are scattered by phonons inside the Co contact, and interfacial thermal conductance is reduced. We also compare the results to the NEGF method. Phonon and magnon scattering rates are incorporated into Büttiker probes attached to the device. The NEGF method shows a similar trend in thermal boundary conductance with spins included. Green's function is solved recursively; therefore, it can be applied to large devices.