Influence of competing energy scales on the effective spin degeneracy in CeNi9−xFexGe4

• Published in: Journal of alloys and compounds 2012-05, Vol.523, p.61-65
• Main Authors: Gold, C., Uffinger, M., Herzinger, M., Eickerling, G., Scherer, W., Michor, H., Scheidt, E.-W.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Critical-point effects, specific heats, short-range order; Crystal and ligand fields; Crystal field; Electron states; Exact sciences and technology; Heavy fermion; Level splitting and interactions; Magnetic properties and materials; Physics; Specific heat; Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.); Strongly correlated systems; heavy fermions
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2012.01.001

► New heavy fermion substitution series CeNi9−xFexGe4 (0≤x≤1). ► Remaining a four-fold degenerate ground state for x≤1. ► Interplay between Kondo-effect, RKKY interaction and crystal field splitting. ► New thermodynamic macroscopic parameter: α=TRln4/TRln2. ► Kondo energy is the dominant electronic control parameter. The interplay between Kondo effect, RKKY interaction and crystal field (CF) splitting in the pseudo-ternary substitution series CeNi9−xFexGe4 (0≤x≤1) is investigated by means of X-ray powder diffractometry and specific heat studies. Contrary to CeNi8CuGe4 and CeNi8CoGe4 no long range magnetic order occurs in CeNi8FeGe4 since it basically retains a four-fold degenerate Kondo lattice ground state similar to its parent system CeNi9Ge4. Kondo screening as well as a modest CF splitting between the two lower energy states (Γ7(1) and Γ7(2)) increase simultaneously with increasing Fe concentration resulting in a Kondo dominated ground state for the whole substitution region. A new parameter α=TRln4/TRln2 is introduced to analyze the interplay between the competing energy scales.