A candidate of a ferromagnetic quantum critical point: an investigation of the Ni_1-xCu_x alloy

In metallic magnetic systems, a second-order phase transition temperature could be tuned to absolute zero by introducing non-thermal tuning parameters, reaching a quantum phase transition where the quantum fluctuations destroy the magnetic order and dominate physical properties therein. In this report, we take an investigation into an itinerant ferromagnetic system, Ni_1-xCu_x alloy. From isothermal magnetization data, we performed an Arrott-Noakes analysis to determine the transition temperature T_C and found T_C→0 in Ni_1-xCu_x with x = 0.66. Strongly chemical disorder is induced as Cu is alloyed with Ni evidenced by a negative temperature coefficient of electrical resistivity, i.e., the resistivity increases slowly as the temperature decreases. The electronic contribution to the specific heat shows divergent behavior as the temperature decreases. These results may indicate an existence of the ferromagnetic quantum critical point in Ni_1-xCu_x, tuned by chemical disorder.