Magnetic anisotropy, first-order-like metamagnetic transitions, and large negative magnetoresistance in single-crystal Gd₂PdSi₃

Abstract

Electrical resistivity (ρ), magnetoresistance (MR), magnetization, thermopower, and Hall-effect measurements on the single-crystal Gd₂PdSi₃, crystallizing in an AlB₂-derived hexagonal structure, are reported. The well-defined minimum in ρ at a temperature above Néel temperature (T_N=21K) and large negative MR below ~3T_N, reported earlier for the polycrystals, are reproducible even in single crystals. Such features are generally uncharacteristic of Gd alloys. In addition, we also found interesting features in other data, e.g., two-step first-order-like metamagnetic transitions for the magnetic field along [0001] direction. The alloy exhibits anisotropy in all these properties, though Gd is an S-state ion.