Galvanomagnetic Properties of Gallium at Low Temperatures

Abstract

The galvanomagnetic properties of gallium single crystals in a transverse magnetic field have been investigated at helium temperatures, 77°K and 290°K. At 290°K and 77°K the galvanomagnetic properties are described according to a set of phenomenological equations, these properties then being specified by the tensors in the equations. This formalism breaks down at helium temperatures, where an apparent reduction in crystal symmetry occurs; the number of coefficients specifying the magnetoresistivity tensor according to crystal symmetry considerations is insufficient for a description of the observed galvanomagnetic properties. The results at helium temperatures can be qualitatively understood in terms of the recent fundamental theory of galvanomagnetic effects of Lifshitz, Azbel', and Kaganov which is based on considerations involving the topology of the Fermi surface. The anomaly of a marked displacement of the maximum in the Hall rotation curve at 77°K and 290°K is accounted for in detail according to the phenomenological formalism, on the basis of the anisotropy of the Hall coefficients at those temperatures combined with a small displacement of crystallographic axes from specimen axes. Well-defined oscillations in the magnetoresistance and Hall effects, superposed on the monotonic variation of the effects, have been observed for every crystal orientation studied. The general characteristics of these oscillations are the same as those in the diamagnetic susceptibility (the de Haas-van Alphen effect).