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Abstract:
The interplay of antiferromagnetic (AFM) and Kondo effect in Ce8Pd24Al with the dilution of Ce with La is investigated by means of electrical and thermal transport and magnetic properties measurements. X - ray diffraction studies confirm a cubic AuCu3 - type crystal structure with space group Pm (3) over barm for all compositions in the alloy series (Ce1-xLax)(8)Pd24Al (0 <= x <= 1). Electrical resistivity, rho(T) results show evolution from coherent Kondo lattice scattering with a well defined Kondo peak at T-max to incoherent single-ion Kondo scattering with increasing La content x. Magnetoresistivity MR measurements on Ce dilute alloys are negative and analyzed based on the calculations by Schlottmann for the Bethe - ansatz in the framework of the Coqblin - Schrieffer model and yield values of the Kondo temperature T-K and the effective moment of the Kondo ion mu(K). The decrease of T-max and T-K is described by the compressible Kondo lattice model. The thermoelectric power, S(T) measurements are interpreted within the phenomenological resonance model. The Lorentz number, L/L-0 increases rapidly on cooling the samples and reaches a maximum value around 6 K. The magnetic susceptibility, chi(T) data at high temperature follow the Curie - Weiss behaviour and yield effective magnetic moments, mu(eff) values across the series close to the value of 2.54 mu(B) expected for the free Ce3+ - ion. The low temperature chi(T) shows an AFM anomaly associated with a Neel temperature T-N for alloys in the range 0 <= x <= 0.2. No metamagnetic transition was observed from the magnetization results, M(mu H-0).
