Change in the Resistivity of bcc and bct FeRh Alloys at First-Order Magnetic Phase Transitions

First-order magnetic phase transitions in the body-centered tetragonal (bct) FeRh 1- x Pt x and bcc FeRh 1- y M y (M=Ir, Fe) systems were studied by means of electrical resistivity and magnetization measurements. The resistivity exhibits an abrupt decrease of 7∼43% at the first-order transition temperature from the antiferromagnetic to the ferromagnetic state or the Curie paramagnetic state in these systems. This discontinuous change is interpreted in terms of the scattering of conduction electrons through the s-d exchange interaction by magnetic moments.