Investigation of heavy fermion and dense Kondo systems in Ce-based ternary silicides

摘要

Measurements of the magnetic contribution to the electric resistivity, static magnetic susceptibility, and low temperature heat capacity of CePtSi are reported in this work. A logarithmic increase of magnetic resistivity is observed with the decrease of temperature in the higher temperature region. This is one of the characteristic features of dense Kondo system. This compound has a large value of the low-temperature magnetic susceptibility ((chi)(,m)(2.4K) = 24.9 x 10(\u27-3) cm(\u273)/mol) and, characteristic of heavy fermion compounds, an enormous coefficient of the electronic specific heat, (gamma) (TURN) 800 mJ/ mol K(\u272). AC magnetic susceptibility measurements indicate that this compound neither orders magnetically nor is superconducting above 70 mK;To understand the nature and mechanism of the heavy fermion compound CePtSi, a number of isostructural pseudoternary systems are investigated by studying the variations of lattice parameters, static magnetic susceptibility and magnetic contribution to the resistivity;The magnetic properties of narrow band metals ranging from heavy fermions to spin fluctuation compounds to mixed-valence materials are displayed in the series Ce(Pt(,1-x)Ni(,x))Si. The first evidence also has been found for the transition from heavy fermion behavior to a ferromagnetic dense Kondo state in the static magnetic susceptibility and resistivity in the series CePt(,x)Si. These studies confirm that f-ligand hybridization is associated with the formation of the heavy fermion state in the system CePtSi;Lastly, the semi-heavy fermion system CeSi(,x) (1.60 (LESSTHEQ) x (LESSTHEQ) 1.90) is examined. The rapid decrease of the magnetic ordering temperatures resulting in a nonmagnetic state as the f-f atomic separations increase in the region 1.80 (LESSTHEQ) x (LESSTHEQ) 1.90, indicates that;f-ligand hybridization is the dominant mechanism of f-electron delocalization in this system; *DOE Report IS-T-1279. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy.