Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 17: Heavy Fermions
TT 17.9: Talk
Wednesday, March 28, 2007, 16:15–16:30, H18
Ferromagnetism in the layered Kondo system CeRuPO — •Cornelius Krellner1, Nagesh Kini2, Eva Maria Bruening1, Michael Nicklas1, Michael Baenitz1, and Christoph Geibel1 — 1Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany — 2Department of Applied Chemistry, Hiroshima University, Higashis-Hiroshima 739-8527, Japan
Intermetallic Kondo lattice systems have attracted considerable attention in the last decades. While there exist many Ce-based compounds showing antiferromagnetic ground states, only very few systems are known which exhibit ferromagnetic order. On the way to find new Ce-based Kondo lattices close to a ferromagnetic quantum phase transition, the CeTPO (T=transition metal) compound series attracted our interest, because of the rather unusual crystal structure with alternating layers of TP4 and OCe4 tetrahedra. In this contribution, we will present the first investigations of the physical properties of CeRuPO crystallizing with the tetragonal ZrCuSiAs type structure (P4/nmm). Measurements of the magnetic susceptibility reveal that Cerium is in a trivalent state with a ferromagnetic transition at TC=15 K which is confirmed in the temperature dependence of specific heat. A pronounced decrease of the resistivity below 50 K and enhanced thermopower S(10 K) = 10 µV/K confirm the presence of Kondo interaction. Detailed study of 31P NMR and results of the magnetization under pressure up to 2 GPa will be discussed. In addition, we show first investigations of the physical ground states of the isostructural compounds CeTPO (T = Os, Fe, Co).