Magnetoconductivity and Polar Scattering in Moderately Ionic Crystals

Abstract

The dc transport problem in a polar crysal, in the range of optical mode scattering, is studied within a weak-coupling model for the electron-phonon interaction. A full variational calculation is performed in the presence of a magnetic field and carried out to high accuracy on a digital computer. It is stressed that the physical effects should be discussed in "magnetoconductivity," rather than conventional "magnetoresistivity" terms, corresponding to the type of experimental arrangement frequently used for these materials. The model, which is, in principle, restricted to a small coupling constant ($\alpha \ll 1$), has some interesting dispersive properties and is used as a working tool for an over-all picture of the transport problem in its full complexity, when a magnetic field is present. Some experimental aspects are discussed and it is suggested that a heuristic correction to the weak-coupling formulas might extend its practical range of applicability to higher values of $\alpha$. This is illustrated with applications to AgBr and AgCl, where $\alpha \approx 2$.