H/T scaling in heat capacity and magnetization in Ce_0.6Y_0.4NiGe₂ compound

Investigation of magnetization, thermodynamic, and transport properties have been carried out on a series of compounds Ce_0.9Y_0.1NiGe₂ (Y-0.1), Ce_0.8Y_0.2NiGe₂ (Y-0.2) and Ce_0.6Y_0.4NiGe₂ (Y-0.4) under the influence of external magnetic field (0 to 14 T). Two antiferromagnetic (AFM) ordering at 3.9 and 3.1 K observed in parent CeNiGe₂ compound is suppressed to ∼ 3 and 2.2 K for Y-0.1 compound, whereas a single transition at 2 K is observed for Y-0.2 compound. For the extreme composition i.e. Y-0.4 compound, the transition temperature is suppressed below 1.8 K. For Y-0.4 compound it is observed that the magnetic entropy increases with increasing magnetic field upto ∼ 1 T. Resistivity also increases with field implying a presence of magnetic field induces the spin disorder. The field (H) and temperature (T) dependence heat capacity and magnetization obey H/T scaling, with critical parameter 5 δ 1.3, implying the presence of an anomalous quantum critical region near the critical field (H_C) of 1 T. The deviation of 5 from 5 =3, which is mean field value of exponent, suggests to onset of local moment. Hence, quantum criticality in Y-0.4 compound is being governed by spin disorder due to non-local fluctuation of f-electron. (author)