Longitudinal magnetoresistance of Ce(Cu_1-xNi_x)₂Si₂

The longitudinal magnetoresistance (LMR) of polycrystalline Ce(Cu_1-xNi_x)₂Si₂ samples is investigated between T = 2 and 15 K up to H = 80 kOe. The application of magnetic field induces anomalous temperature dependence of the resistivity with the power index n < 2 for x = 0.12 and 0.14, in which ρ(T) obeys a T ²-law at H = 0 Oe. A sign-change of the LMR from positive (x < 0.03) to negative (x > 0.03) is observed at 2 K. The negative LMR at 80 kOe is maximized (∼ -4 % at T = 2 K) around x ∼ 0.10 and subsequently disappears at higher Ni concentrations. Disappearance of the positive LMR in lower x region and the negative LMR at higher Ni concentrations implies a collapse of a coherent Kondo lattice state, and a rapid enhancement of Kondo temperature, respectively. Anomalous quantum fluctuations are probably developed around x ∼ 0.10.