that are manifested on a macroscopic scale as a thermal boundary resistance (TBR), also called Kapitza resistance, $R_k$, that relates the temperature drop at the interface to the heat flux flowing across it. TBR exists at the interface between any dissimilar materials due to differences in phonon states on each side of the interface.[@Swartz1989] Typical interfaces often possess defects or roughness which can lead to additional phonon reflections and hence higher TBR.

TBR plays an increasingly important role in applications, particularly as device sizes decrease below the intrinsic mean free paths (MFPs) of thermal phonons.[@Cahill2014Review] At sufficiently small length scales, TBR can dominate the total thermal resistance. For instance, the effective thermal conductivity of a superlattice can be orders of magnitude smaller than that of the constituent materials due to TBR.[@pettersson_theory_1990; @Chen1998; @Ravichandran2014; @Chen2013] This physical effect has been used to realize thermoelectrics with high efficiency[@SciencePaper; @Biswas2012] and dense solids with exceptionally low thermal conductivity[@Chiritescu2007]. On the other hand, TBR can lead to significant thermal management problems[@Pop2010; @Moore2014; @Cho2015] in applications such as LEDs[@Su2012; @Han2013] and high power electronics[@Yan2011; @Cho2015].

Numerous works over several decades have investigated the microscopic origin of TBR at solid-solid interfaces, starting with studies performed at 