Study of the Ce(Rh₁₋ₓPdₓ)₂Si₂ alloy: evidence for itinerant character of the magnetic order in CeRh₂Si₂

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We present electrical resistivity and specific heat measurements of alloys on the Rh rich side of the phase diagram of the Ce(Rh₁₋ₓPdₓ)₂Si₂ system and compare the results with those obtained at intermediate and low Rh concentrations. The analysis of the x-evolution of the entropy and the scaling behaviour of Cel(T) and ρ(T) clearly confirm a separation of the magnetic phase diagram into two regions. The region x≤0.3, showing a concentration independent characteristic temperature Tₒ≈45 K, while for x>0.3 Tₒ decreases down to Tₒ(x=1)≈15 K. This characteristic temperature is obtained by scaling the Cel(T,x>0.3) results as a function of the reduced temperature T/Tₒ. At low Pd-content, Tₙ decreases very rapidly from Tₙ = 36 K in pure CeRh₂Si₂ to Tₙ=18 K at x=0.1. With higher Pd concentration it stabilized at Tₙ≈15 K whereas the magnitude of the anomalies in Cel(T) and in the susceptibility around Tₙ are further reduced and disappear at x≈0.3. This is in contrast to the behavior found on the Pd-rich side, where Tₙ decreases continuously to zero with increasing Rh content. The pronounced differences observed between both phase boundaries and the drastic effect of doping on the Rh rich side suggest an itinerant character in CeRh₂ Si₂, in contrast to the localized character of CePd₂Si₂. A further evidence for the itinerant character in CeRh₂Si₂ is given by the ρ(T) dependence observed for x≤0.3, which scales with ρ(T) of the prototype itinerant compound YCo₂.