HALL-EFFECT AND THERMOELECTRIC-POWER IN UNIGA

We report on simultaneous measurements of the magnetization, magnetore sistance, Hall effect and thermoelectric power on single-crystal UNiGa to investigate the origin of giant magnetoresistance phenomena. The n ounal part of Hall coefficient is markedly different above and below t he metamagnetic transition at low temperatures. The thermoelectric pow er at 4.2 K changes its sign between the two magnetic states. Those re sults imply that the strong resistivity variations are intimately conn ected with a reconstruction of the Fermi surface across the transition .