Thermal characteristics in a nanometer scale

As examples of studies on thermal characteristics of materials with a nanometer scale two topics are discussed. One is heat capacity and thermal conductivity of small materials at low temperatures. It based upon the recent findings that heat capacity depends on the limited number of the phonon modes in low angular frequency region and the distinct characteristic is the appearance of quantized thermal conductance in heat transfer through a narrow wire with hundreds nm. The other is the thermophysical properties at the ordinary interface. The disordered structure appearing in the interfacial region with a width of a few nm is discussed, which is comparable to the phonon mean free path, should be taken into account to reveal the characteristic thermal behavior at room temperature.