Reduction of thermal conductivity in MnSi1.7 multi-layered thin films with artificially inserted Si interfaces

Abstract

We report a lowered lattice thermal conductivity in nm-scale MnSi1.7/Si multilayers which were fabricated by controlling thermal diffusions of Mn and Si atoms. The thickness of the constituent layers is 1.5–5.0 nm, which is comparable to the phonon mean free path of both MnSi1.7 and Si. By applying the above nanostructures, we reduced the lattice thermal conductivity down to half that of bulk MnSi1.7/Si composite materials. The obtained value of 1.0 W/K m is the experimentally observed minimum in MnSi1.7-based materials without any heavy element doping and close to the minimum thermal conductivity. We attribute the reduced lattice thermal conductivity to phonon scattering at the MnSi1.7/Si interfaces in the multilayers.