Giant magnetoresistance and field-induced magnetic phase transitions in Gd7Rh3 studied on single crystals

Magnetization measurements in steady and pulsed fields and magnetoresistance measurements in different field-current geometries on single crystalline samples have been employed to study the field-induced magnetic phase transitions in the antiferromagnetically (AF) ordered compound Gd7Rh3 with hexagonal crystal structure of the Th7Fe3 type. Below TN = 141 K, the magnetic structure transformations from AF to the forced ferromagnetic (FF) state, which are accompanied by a giant reduction of the electrical resistivity (up to 7 times at low temperatures), were observed under the magnetic fields along the c-axis and in the basal plane. This giant magnetoresistance is associated with magnetic superzone effects. The negative temperature coefficient of the electrical resistivity and a large magnetoresistance were also observed in the paramagnetic region in Gd7Rh3; which are suggested to result from the retention of short-range AF correlations in a wide temperature range above TN.