The weak itinerant ferromagnetic behavior of Y${}_2$Ni${}_7$ is investigated through magnetic, transport, and calorimetric measurements. The low value of the saturation moment, large Rhodes-Wohlfarth ratio, large value of the linear term in heat capacity, and Fermi-liquid-like resistivity behavior with enhanced electron-electron scattering contribution establish firmly the weak itinerant ferromagetic nature of the sample. The critical exponents associated with the paramagnetic-to-ferromagnetic transition are also investigated from magnetization isotherms using modified Arrott plot, Kouvel-Fisher plot, and critical isotherm technique. The more accurate Kouvel-Fisher plot provides the critical exponents to be $\beta =0.306$ ($\pm$0.002), $\gamma =1.401$ ($\pm$0.02), and $\delta =5.578$. These values differ markedly from the mean-field values and correspond closely to the two-dimensional Ising spin system with long-range spin-spin interactions.

• Received 30 May 2011

DOI:https://doi.org/10.1103/PhysRevB.84.184414