Model Calculation of Optical Dephasing in Glasses

Abstract

In 1971, Zeller and Pohl [2] presented experimental evidence that thermal conductivity and heat capacity of several insulating glasses show a behavior differing strikingly from that of their crystalline counterparts. Earlier measurements [3–5] which had already pointed at these facts had not found much notice. Before 1970, it was believed by most scientists that the low-temperature properties of glasses were similar to those of crystals, because the microscopic structure of a material should become unimportant with increasing phonon wavelength. The results of Zeller and Pohl — a linear temperature dependence of the (phonon part of the) heat capacity and a T 2 dependence of the thermal conductivity with an order of magnitude almost independent of materials — were therefore extremely interesting and triggered off a large number of experimental studies and theoretical explanations.