Quantum critical point in the itinerant ferromagnet Ni$_{1-x}$Rh$_x$

Abstract

We report a chemical substitution-induced ferromagnetic quantum critical point in polycrystalline Ni 1−x Rh x alloys. Through magnetization and muon spin relaxation measurements, we show that the ferromagnetic ordering temperature is suppressed continuously to zero at x crit = 0.375 while the magnetic volume fraction remains 100% up to x crit , pointing to a second order transition. Non-Fermi liquid behavior is observed close to x crit , where the electronic specific heat C el /T diverges logarithmically, while immediately above x crit the volume thermal expansion coefficient α V /T and the Grüneisen ratio Γ = α V /C el both diverge logarithmically in the low temperature limit, further indication of a ferromagnetic quantum critical point in Ni 1−x Rh x .