Samsung Advanced Institute of Technology

Unlike many superlattice structures, Ruddlesden-Popper phases have atomically abrupt interfaces useful for interrogating how periodic atomic layers affect thermal properties. Here we measure the thermal conductivity in thin films of n = 1 ？ 5 and 10 (SrTiO₃)_nSrO Ruddlesden-Popper superlattices grown by molecular-beam epitaxy and compare the results to a single crystal of the n = 1 Ruddlesden-Popper SrLaAlO₄. The thermal conductivity cross-plane to the superlattice layering (k₃₃) is measured using time-domain thermoreflectance as a function of temperature and the results are compared to first-principles calculations. The thermal conductivity of this homologous series exhibits saturation below n = 3 (~2.0 W m^？1 K^？1). Characterization by x-ray diffraction and scanning transmission electron microscopy confirm that these samples have a Ruddlesden-Popper superlattice structure.