Interplay of antiferromagnetism and Kondo effect in (Ce1−xLax)8Pd24Al

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 Pm3¯m for all compositions in the alloy series (Ce1−xLax)8Pd24Al(0≤x≤1). Electrical resistivity, ρ(T) results show evolution from coherent Kondo lattice scattering with a well defined Kondo peak at Tmax 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 TK and the effective moment of the Kondo ion μK. The decrease of Tmax and TK 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/L0 increases rapidly on cooling the samples and reaches a maximum value around 6 K. The magnetic susceptibility, χ(T) data at high temperature follow the Curie - Weiss behaviour and yield effective magnetic moments, μeff values across the series close to the value of 2.54 μB expected for the free Ce3+ - ion. The low temperature χ(T) shows an AFM anomaly associated with a Néel temperature TN for alloys in the range 0≤x≤0.2. No metamagnetic transition was observed from the magnetization results, M(μ0H).