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TT: Tiefe Temperaturen
TT 16: Postersitzung II: Amorphe und Tunnelsysteme, Mesoskopische Systeme, Schwere Fermionen, Kernmagnetismus
TT 16.35: Poster
Tuesday, March 27, 2001, 14:30–17:00, Rang S\ 3
Possible spin-glass type quantum critical point in La1−xCexCu2Si2 — •Adriana Sanchez, Jeroen Custers, Philipp Gegenwart, Christoph Geibel, Silke Paschen, and Frank Steglich — MPI für Chemische Physik fester Stoffe, Nöthnitzer Str. 40, D - 01187 Dresden
Polycrystalline samples of La1−xCexCu2Si2 for differents x values have been investigated previously by other authors. For x=0.1, non-Fermi-liquid (NFL) behaviour has been detected in susceptibility, specific-heat and resistivity measurements. Subsequently, it was proposed that the Ce3+ impurities in this x=0.1 alloy are subject to a magnetic two-channel Kondo effect, a hallmark of which is a giant negative thermopower (TEP) peak at low temperatures. However, the experimental observation of a giant positive TEP peak at T=9K seemed to discard this possibility and rather pointed to a different origin of the NFL phenomena observed at low temperatures. For La1−xCexCu2Si2 samples at x>0.15, evidence was found for a low-T spin-glass transition. We are currently verifying the spin-glass behaviour at low temperatures. Our aim is to determine the concentration xc where TG is zero. Samples with this critical concentration may be expected to show NFL behaviour due to a spin-glass type quantum critical point.