Mechanism of the Giant Magnetoresistance in UNiGa from First-Principles Calculations

The giant magnetoresistance (MR) in UNiGa is investigated from first principles, using density-functional band-structure theory in the local approximation together with a linear-response ansatz for the conductivity. The MR is calculated to be very anisotropic, with a large value of {minus}(45{plus_minus}5){percent} for current in plane and a giant MR of {minus}(64{plus_minus}5){percent} for current perpendicular to plane. These values are in semiquantitative agreement with the measured MR. The basic mechanism of the giant MR is identified to be a superzone reconstruction of the Fermi surface at the field induced metamagnetic transition. {copyright} {ital 1996 The American Physical Society.}