Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 17: Heavy Fermions
TT 17.4: Vortrag
Mittwoch, 28. März 2007, 14:45–15:00, H18
Study of a smeared ferromagnetic quantum phase transition in CePd1−xRhx single crystals — •Micha Deppe1, Tanja Westerkamp1, Adam Pikul1, Nubia Caroca-Canales1, Christoph Geibel1, Robert Küchler1, Philipp Gegenwart1, and Julian Sereni2 — 1Max-Planck-Institute for Chemical Physics of Solids, 01187 Dresden, Germany — 2Lab. Bajas Temperaturas, Centro Atómico Bariloche (CNEA), 8400 S.C. de Bariloche, Argentina
Appropriate Cerium based compounds for the study of a ferromagnetic (quantum) critical point are extremely scarce. On the other hand the orthorhombic alloy CePd1−xRhx shows a continuous decrease of the ferromagnetic transition temperature TC (x) from 6.6 K for x = 0 to 0.025 K at x = 0.87. Detailed low temperature measurements of CePd1−xRhx polycrystalline samples showed an extended range of non-Fermi liquid behavior between 0.85 ≤ x ≤ 0.9, suggesting a smeared ferromagnetic quantum phase transition near xcr ≈ 0.87. We extended our studies on CePd1−xRhx single crystals, which allow to include anisotropy effects in the study and analysis of this system. The anisotrophy is quite strong for x ≤ 0.6 with the easy axis along the c-direction, but decreases rapidly for x ≥ 0.7. Furthermore the ferromagnetic signal in the ac-susceptibility becomes frequency dependent at x ≥ 0.72 supporting a suppression of long-range magnetic order. We explain the unusual magnetic behavior of CePd1−xRhx with a distribution of local Kondo temperatures near xcr due to disorder introduced by Pd → Rh exchange and the formation of a "Kondo - Cluster glass".