Thermal-expansion effects in electrical transport in amorphous metals

Theoretical treatments of electrical transport in amorphous metals are usually performed at constant volume, although most experimental studies are performed at constant pressure. Recent studies of the influence of pressure on the electrical resistivity of a variety of amorphous metals indicate that thermal-expansion effects cannot be ignored in a theoretical description of the temperature dependence of the isobaric resistivity. In this paper, general ideas pertinent to a theoretical description of nonisochoric electrical transport are presented. Results for isobaric electrical transport based on the Grüneisen theory of thermal expansion, which are independent of the model employed to treat isochoric transport, are also given. The implications of the theory are illustrated in the context of the diffraction model by (1) detailed results specific to the well-characterized low-resistivity alloy, a-${\mathrm{Mg}}_7$ ${\mathrm{Zn}}_3$, and (2) a selection of model calculations incorporating thermal-expansion effects for cases with positive and negative pressure coefficients of resistivity.