Crystal fields and Kondo effect: Specific heat for Cerium compounds

Abstract

The thermodynamic Bethe ansatz equations for the N = 6 Coqblin-Schrieffer model with crystal fields have been solved numerically. The realistic case of three Kramers doublets with arbitrary splittings has been studied for the first time. The specific heat has been calculated for representative combinations of the ionic energy splittings providing ample material for comparison with experimental results for Cerium impurities and compounds.

ARPES view on surface and bulk hybridization phenomena in the antiferromagnetic Kondo lattice CeRh2Si2

“…A preliminary survey of the results in ref. 38 suggests that the curve for Δ 1 =1/2̇Δ 2 =0.7· T KN6 is closest to our experimental data. Matching experimental and calculated C 4 f ( T ) in the T range 50<250 K resulted in T KN6 =50 meV.…”

“…Therefore, we determined C 4 f  ( T ) and S 4 f ( T ) of CeRh 2 Si 2 in a wide T range, up to 300 K, and compared with the curves expected for different CEF schemes and different values of the Kondo temperature T K (Fig. 5)38. There is presently no analytical expression available for the specific heat of a Kondo lattice which includes both AFM order and the Kondo effect on the excited CEF levels.…”

“…Fortunately, Desgranges38 very recently provided such numerical results for a larger number of cases, and therefore we tried to use them for modelling our experimental C 4 f  ( T ) data. In this approach, one has first to choose the most appropriate case among those considered in ref.…”

“…In this approach, one has first to choose the most appropriate case among those considered in ref. 38, and then to fix the only free parameter which is the Kondo scale in the absence of CEF splitting, T KN6 . A preliminary survey of the results in ref.…”

“…Desgranges provided us with his numerical results for the Kondo+CEF model for the cases A 2= A 4=0.7 T KN6 and A 4=0, A 2= T KN6 (nomenclature as in ref. 38), which correspond to the cases Δ 2 =2·Δ 1 and Δ 2 =Δ 1 , respectively. T KN6 was scaled in order to get the best match for the specific heat data.…”