Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 32: Correlated Electrons: Poster Session
TT 32.21: Poster
Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B
Uniaxial pressure and strain dependences of the characteristic energies in CeCu6−xAux — •Kai Grube1, Stefanie Drobnik1,2, Roland Schäfer1, Frédéric Hardy1, Christoph Meingast1, Oliver Stockert3, and Hilbert von Löhneysen1,2 — 1Forschungszentrum Karlsruhe, Institut für Festkörperphysik, 76021 Karlsruhe, Germany — 2Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe, Germany — 3MPI für chemische Physik fester Stoffe, 01187 Dresden, Germany
If paramagnetic compounds are driven into a magnetically ordered state by a nonthermal control parameter, the spontaneous symmetry breaking in the ordered state, as well as the interplay of characteristic energies inevitably lead to a change of the anisotropy of the compound at low temperatures. This can be used to identify the dominant energy scales and to study in more detail continuous phase transitions at zero temperature, i.e. so-called quantum critical points (QCP). The archetypical heavy-fermion system CeCu6−xAux is one of the best investigated examples of a magnetic QCP. It can easily be tuned across the onset of antiferromagnetic order by changing its volume either by alloying with Au or applying pressure. For several distinct Au contents we have determined the uniaxial pressure and strain dependences of the Kondo and the magnetic interaction energies, with the Grüneisen parameter obtained through thermal expansion, specific heat, and compressibility measurements. The results show a strongly anisotropic antiferromagnetic phase which develops from a nearly isotropic Kondo-lattice state.