High-field galvanomagnetic properties of AuAl2, AuGa2, and AuIn2

Measurements of the magnetoresistance and Hall voltage have been made in the high-field region on the metallic fluorite compounds AuAl2, AuGa2, and AuIn2. The results have been compared with those expected from the nearly-free-electron (NFE) model. These compounds are uncompensated. The magnetoresistance measurements in principal planes and directions, with one exception, support the NFE model, but the dimensions of the two-dimensional areas of aperiodic open orbits show pronounced deviations. Hall-effect measurements for B in the 100 and 111 directions indicate significant departures of the real Fermi surface from the NFE model. A proposed empirical model gives much better agreement with Hall-effect, magneto-resistance, and de Haas-van Alphen measurements. In the best AuGa2 crystal, magnetoresistance whiskers have been observed and classified in some detail. The magnetoresistance has been calculated for B in the {100} plane, assuming a constant relaxation time and a model of the fourth electron zone with a topography similar to the NFE Fermi surface.