Anomalous positive magnetoresistance at low temperatures in nanocrystalline Ni₃Al

Abstract

Reducing the crystallite size to ≅ 45 nm drives the weak itinerant-electron ferromagnet Ni₃Al to magnetic instability, where long-range ferromagnetic order collapses. Non-Fermi-liquid behavior of resistivity, ρ(T), at temperatures 4 K<=T<=22 K, an abrupt drop in ρ(T), and a sudden increase in positive magnetoresistance at T≲4 K (presumably due to antiferromagnetic-spin fluctuation-mediated superconductivity) in nanocrystalline Ni₃Al indicates that the crossover region near the magnetic quantum critical point extends to temperatures as high as 4 K.