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.
Highlights
The origin of spin caloritronics is the so-called spin Seebeck effect (SSE) related to the generation of spin voltage driven by a temperature gradient
Spin–lattice interactions are quantified through exchange interactions between spins, and the exchange constants are obtained from first-principles calculations
We present a method of calculating thermal boundary conductance between heterogeneous materials by integrating first-principles exchange constants and spin–lattice dynamics into the non-equilibrium Green’s function (NEGF) method, and we apply the method to bulk Co and a
Summary
The origin of spin caloritronics is the so-called spin Seebeck effect (SSE) related to the generation of spin voltage driven by a temperature gradient. Both conduction electrons and spin waves (magnons) carry spin currents, but the range of the former is only hundreds of nanometers while the latter can persist for millimeters. In the area of heat transport, magnon–phonon interactions offer potential applications in engineering thermal devices with magnetic materials. The effect of magnon– magnon and magnon–phonon interactions on the thermal conductivity of BCC iron was modeled by combining molecular dynamics and spin dynamics. We present a method of calculating thermal boundary conductance between heterogeneous materials by integrating first-principles exchange constants and spin–lattice dynamics into the non-equilibrium Green’s function (NEGF) method, and we apply the method to bulk Co and a
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