R. C. Dynes

Ballistic Phonons and the Transition to Second Sound in Solid 3He

We report a study of heat pulse propagation in solid 3He as a function of temperature (between .05K and .5K) and molar volume (24.5 cm3/mole to 23.7 cm3/mole). We use the fast heat pulse technique(1) and present data which shows the transition from ballistic flow to second sound. We present evidence for unusual behaviour in the temperature dependence of the velocity and intensity of the slow transverse phonon (propagating close to [110]). The implication of these measurements for specific heat data(2) are discussed.

Weak Localization in Silicon Mosfets: Isotropic and Anisotropic Two-Dimensional Electron Gases

In this paper we review measurements in the weak localization regime of silicon mosfets. We first present data on isotropic (100 and 111) devices and discuss the magnetoresistance and temperature-dependent resistivity which provide support for the scaling theory of localization in two dimensions. We then discuss more recent measurements on anisotropic devices (110) which provide the first parameter-free test for the scaling theory in two dimensions.

The time dependent specific heat of dielectric glasses

Abstract Measurements on the time dependence of the specific heat exist now both at short and long timescales. Below 0.3 K the short time (}10 μs) specific heat of all the materials studied is smaller than the long time specific heat, but larger than the Debye value. Above 0.2 K most of the specific heat is coupled to the phonons already at 10 μs. However, measurements at very long timescales reveal that the specific heat has a component with a logarithmic time dependence, as proposed by the tunneling model, although only part of the total specific heat can be ascribed to it.