Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 35: Correlated Electrons: Quantum-Critical Phenomena - Experiment I
TT 35.6: Vortrag
Dienstag, 1. April 2014, 10:45–11:00, HSZ 204
Frustrated magnetic order in CePd1−xNixAl studied by neutron diffraction — •Z. Huesges1, S. Woitschach1, O. Stockert1, V. Fritsch2, M.-H. Lemée-Cailleau3, S. Capelli3, S. Matas4, K. Prokes4, B. Pedersen5, and H. von Löhneysen2 — 1Max Planck Institute CPfS, Dresden, Germany — 2Karlsruhe Insitute of Technology, Germany — 3Institut Laue-Langevin, Grenoble, France — 4Helmholtz Zentrum Berlin, Germany — 5FRM2, Technical University München, Germany
The heavy-fermion compound CePdAl might be a model system to study the influence of frustration on quantum criticality, which has recently become a much-discussed topic in theoretical condensed matter physics. The quantum critical point can be accessed by Ni doping on the Pd site, which reduces the Néel temperature from 2.7 K in the pure compound to zero for 14 % Ni substitution. The magnetic order of undoped CePdAl has previously been investigated by powder neutron diffraction, which revealed that only two thirds of the Ce spins order, while the ordered moment of the remaining third is zero even at very low temperatures. This frustration can be related to the quasi-Kagomé lattice of the Ce ions in the hexagonal basal plane. We have performed single crystal neutron diffraction for different alloys of the doping series CePd1−xNixAl. We found that the ordering vector remains unchanged upon doping and that the ordered moment is gradually suppressed. Furthermore, we observed short-range magnetic order which co-exists with the long-range order signal. The length scale of these fluctuations becomes much shorter on approaching the quantum critical point.