Crystal-field excitations inCeCu2Si2

Theoretical Prediction and Spectroscopic Fingerprints of an Orbital Transition inCeCu2Si2

“…3 (a) are due to empty (or weakly occupied) CF states, their positions with respect to the Fermi level define the renormalized CF splitting. The calculated zero-pressure CF splitting of about 40 meV is in agreement with the experimental value of 30-37 meV [27][28][29] and exhibits a moderate increase with P, with the orbital character of the second CF peak switching across the transition. A similar evolution is observed as function of temperature at the ambient pressure [35]: a Kondo peak of the j0i character at T ¼ 7 K transforms into a two-peak structure and shifted away from E F at higher T. However, in this case one sees no clear Kondo resonance of the orbital character j2i at T ≥ 14 K in agreement with experimental estimates T K ≈ 10 K for CeCu 2 Si 2 at ambient P [27].…”

Unconventional Superconductivity and Magnetism in Lanthanide and Actinide Intermetallic Compounds

“…As long as we work sufficiently close to the transition temperature, where a Ginzburg-Landau expansion is valid the systematic construction of gap functions in terms of basis functions which are invariant under subgroups is a useful guideline. Exhaustive lists of the superconducting classes for the relevant crystal symmetries were given by Volovik and Gor'kov (1985), Ueda and Rice (1985) , Blount (1985), Gorkov (1987), Sigrist and Ueda (1991), Annett (1990) and Ozaki and Machida (1985), Machida and Ohmi (1998), Machida et al (1999) and references cited therein. A recent summary is found in the textbook of Mineev and Samokhin (1999).…”

“…It consists of ellipsoids and modulated columns which are oriented parallel to the tetragonal axis. The calculations adopt the CEF scheme suggested by Goremychkin and Osborn (1993) consisting of a singlet ground state separated from an excited quartet by a CEF splitting δ ∼ 340 K. Therefore δ ≫ T * ≃ 10 K (obtained from the γ-value). Consequently quasiparticle properties are strongly anisotropic.…”

Slow crossover inYbXCu4(X=Ag, Cd, In, Mg, Tl, Zn) intermediate-valence compounds

“…Determination of the magnetic scattering in polycrystals of IV compounds requires correct subtraction of the nonmagnetic scattering. We have adopted a variant on the conventional procedure 21 for accomplishing this where the YXCu 4 (and/or LuXCu 4 ) nonmagnetic counterpart to the corresponding YbXCu 4 sample is measured to determine the factor h(∆E) = S(high Q; ∆E;Y)/S(low Q; ∆E;Y) by which the high-Q scattering (which is almost totally nonmagnetic scattering) scales to the low Q values where the magnetic scattering is strongest. This factor varies smoothly from a value ∼4-5, at ∆E = 0, to a value of 1 at large ∆E where Q-independent multiple scattering dominates the nonmagnetic scattering.…”