Synthesis and Magnetic Properties of Ni3AlCx

The itinerant-electron ferromagnet Ni3Al and its carbon-intercalated compounds Ni3AlCx (x = 0.01, 0.02, 0.04, 0.05, 0.08, and 0.1) were synthesized and investigated by magnetization measurements between 2 and 300 K with the magnetic field H up to 5 T and Al-27 NMR measurements at H = 7.4847 T. The Curie temperature is suppressed and disappears only by the carbon intercalation with x = 0.02. For the samples with x <= 0.02, the T-4/3-temperature dependence of M-s(2) (M,: spontaneous magnetization) and chi(-1)(0) (chi(0): initial susceptibility) are newly observed, being consistent with the predication of the self-consistent renormalization theory of spin fluctuations for weak itinerant ferromagnets. The coupling constant between the Al-27 Knight shift and the bulk susceptibility of Ni3AlC0.1 is three times larger than that of Ni3Al, suggesting the drastic change of the electronic state by the carbon intercalation.