Interfacial thermal conductance between a spin-ladder cuprate (La5Ca9Cu24O41) and a metal film: the role of surface defects in cuprates

Abstract

Thermal switching is an invaluable technique for advanced thermal management and enables highly efficient reuse of thermal energy and improves the performance of various devices that are impacted by waste heat. Spin-ladder cuprate, La₅Ca₉Cu₂₄O₄₁ (LCCO), is ideal for thermal switching owing to its intrinsic high thermal conductivity due to magnons and its tunability; however, its tunability has not been fully explored yet and is crucial for the practical application of spin-ladder cuprates. Herein, a recoverable change in the interfacial thermal conductance between the ab face of the LCCO single crystal and a metal film was achieved by applying and reversing voltage using water, as revealed by frequency-domain thermoreflectance. Secondary ion mass spectrometry and X-ray photoelectron spectroscopy results were used to propose a plausible model, in which the generation of H₂ by water electrolysis and its subsequent reaction with adsorbed oxygen to form H₂O caused a decrease in the interfacial thermal conductance, while the reverse reaction enabled its recoverability. This proposed method will pave the way for the practical application of spin-ladder cuprates in thermal switching.