Large Negative Magnetoresistance of the Rare-Earth Transition-Metal Intermetallic Compound PrMnSi₂

The rare-earth intermetallic compound PrMnSi 2 consists of two magnetic sublattices, i.e., layers of Mn atoms and layers of Pr atoms, which repeat in the (−Mn−Pr−Pr−) ∞ sequence. Electrical resistivity measurements were carried out for PrMnSi 2 between 2 and 350 K under various magnetic fields. PrMnSi 2 is a metal with two metal-to-metal transitions at ∼20 and ∼50 K, and its resistivity vs temperature curves show a significant hysteresis in the absence and presence of an external magnetic field. The resistivity is reduced by an external magnetic field, and this negative magnetoresistance reaches up to 47% at 9 T around 17 K where PrMnSi 2 is antiferromagnetic at zero field. The magnetoresistance vs temperature curves of PrMnSi 2 reveal three peaks at fields up to ∼3 T, which correspond to the three magnetic phase transitions of PrMnSi 2 observed from magnetic susceptibility and heat capacity measurements. The negative magnetoresistance and the resistivity hysteresis of PrMnSi 2 were accounted for by considering how the scattering of the electrons at the Fermi level is reduced by an applied field.