Thermal conductance of interfaces with amorphous SiO2 measured by time-resolved magneto-optic Kerr-effect thermometry

Abstract

We use time-resolved magneto-optic Kerr effect and ultrathin Co/Pt transducer films to perform thermal-transport experiments with higher sensitivity and greater time resolution than typically available in studies of interfacial thermal transport by time-domain thermoreflectance. We measure the interface conductance between Pt and amorphous ${\mathrm{SiO}}_{2}$ using Pt/Co/Pt ferromagnetic transducer films with thicknesses between 4.2 and 8.2 nm and find an average value of ${G}_{\mathrm{Pt}}\ensuremath{\approx}0.3\phantom{\rule{4pt}{0ex}}\mathrm{GW}\phantom{\rule{4pt}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}\phantom{\rule{4pt}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$. This result demonstrates that interfaces between metals and amorphous dielectrics can have a conductance corresponding to Kapitza lengths of the order of 4 nm, and are thus of relevance when engineering nanoscale devices. For thin ${\mathrm{SiO}}_{2}$ layers, our method also provides sensitivity to the interface conductance between ${\mathrm{SiO}}_{2}$ and Si and we find ${G}_{\mathrm{Si}}=0.6\phantom{\rule{4pt}{0ex}}\mathrm{GW}\phantom{\rule{4pt}{0ex}}{\mathrm{m}}^{\ensuremath{-}2}\phantom{\rule{4pt}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ as the lower limit.