Berlin 2015 – wissenschaftliches Programm
TT 71.3: Poster
Mittwoch, 18. März 2015, 15:00–18:00, Poster B
Site dependence of the Kondo scale in CePd1−xRhx evidenced by thermopower — •Ulrike Stockert1, Stefanie Hartmann1, Micha Deppe1, Nubia Caroca-Canales1, Christoph Geibel1, Julian Sereni2, and Frank Steglich1 — 1Max Planck Institute for Chemical Physics of Solids, Dresden — 2Division Bajas Temperaturas, Centro Atómico Bariloche, Argentina
CePd1−xRhx undergoes a continuous evolution from ferromagnetic order in CePd to an intermediate-valence (IV) ground state for CeRh. Close to the disappearance of magnetic order at xcr ≈ 0.87 unusual behavior of the ac susceptibility and the specific heat was observed. It was explained with a broad distribution of local Kondo temperatures TK from below 2 K to above 50 K due to the disorder introduced by Pd-Rh exchange.
The thermopower S is very sensitive to Kondo scattering even for diluted 4f systems. In Ce compounds a large positive maximum in S(T) is usually observed around TK. We studied S(T) in CePd1−xRhx in order to evaluate the presence of Kondo scattering and the involved enery scales. Pure CeRh shows typical IV behavior with a large maximimum at 220 K and small values at low T. Already 5 % Pd substitution leads to a strong enhancement of the low-T thermopower. Even larger values are found around xcr, while the high-T maximum shifts only moderately. Our results are in line with the existence of low (local) Kondo scales in the presence of IV behavior at high Rh content x > xcr. For lower Rh content a decreasing (average) Kondo scale is found.