Evidence for a dimensionality crossover at the disappearance of magnetism in the Kondo lattice alloy CeCo1-xFexSi

Abstract

Structural, magnetic, and thermal measurements performed on CeCo1−xFexSi alloys are reported. Three regions can be recognized: (i) Co rich (x≤0.20) with a decreasing long-range antiferromagnetic order which vanishes at finite temperatures, (ii) an intermediate region (0.20<x≤0.30) showing a broad magnetic anomaly (CA) in specific heat, and (iii) the nonmagnetic region progressively changing from a non-Fermi-liquid-type behavior towards a Fermi-liquid one as Fe concentration increases. The CA anomaly emerges as an incipient contribution above TN already at x=0.10, which indicates that this contribution is related to short-range correlations likely of quasi-two-dimensional type. Both TN transition and CA anomaly are practically unaffected by an applied magnetic field up to B≈10T.