Influence of chemical composition on the X-ray photoemission, thermopower, specific heat, and magnetic properties of CeNi2(Si1-yGey)2

• Published in: Applied physics. A, Materials science & processing Vol. 123; no. 6; pp. 1 - 8
• Main Authors: Toliński, T., Synoradzki, K., Bajorek, A., Chełkowska, G., Koterlyn, M., Koterlyn, G., Yasnitskii, R.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2017; Springer Nature B.V
• Subjects: Applied physics; Characterization and Evaluation of Materials; Chemical composition; Condensed Matter Physics; Electrical resistivity; Machines; Magnetic properties; Manufacturing; Materials science; Nanotechnology; Optical and Electronic Materials; Physics; Physics and Astronomy; Processes; Surfaces and Interfaces; Temperature dependence; Thin Films; Valence; Magnetic Susceptibility; Kondo Temperature; Heavy Fermion; Crystal Electric Field; Quantum Critical Point
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-017-1017-z

We report our studies of the intermediate compositions between CeNi 2 Si 2 and CeNi 2 Ge 2 , i.e., the alloys CeNi 2 (Si 1-y Ge y ) 2 by means of the thermopower, electrical resistivity, specific heat, magnetic susceptibility, and X-ray photoemission measurements. CeNi 2 Si 2 is a fluctuating valence system and CeNi 2 Ge 2 is known to show the heavy fermion behaviour. The change of the temperature dependence of the resistivity towards the typical metallic behaviour occurs below y  ~ 0.25. The transition between CeNi 2 Si 2 and CeNi 2 Ge 2 is discussed in the frames of competition between the crystal electric field and Kondo interactions. It is found that valence stabilisation occurs for Ge content y  > 0.25. The hybridization energy Δ determined from the XPS Ce 3d spectrum reflects well the behaviour of the parameter E ex obtained from the analysis of the magnetic susceptibility by the interconfiguration fluctuation model. It has been also shown that thermopower data can be successfully described employing the single ion model for 0.6 <  y  < 1.0 and two-band model including the crystal electric field splitting for y  ≤ 0.25.