Large negative magnetoresistance of the rare-earth transition-metal intermetallic compound PrMnSi ₂

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.