Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 17: Correlated Electrons: Quantum-Critical Phenomena 1

TT 17.2: Vortrag

Dienstag, 24. März 2009, 14:15–14:30, HSZ 03

Experimental Investigation of Pd1−xNix at the border of Quantum Criticality — •Christian Franz1, Christian Pfleiderer1, Michael Schulz1,2, Björn Pedersen2, and Peter Böni11Physik Department E21, Technische Universität München, D-85748 Garching, Germany — 2Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, D-85748 Garching, Germany

Polycrystals of the transition metal system Pd1−xNix display ferromagnetic quantum criticality at a critical concentration xc assumed to be well described by the SCR theory. We report comprehensive studies of the magnetic field and temperature dependence of the magnetization, resistivity, Hall effect and specific heat of Czochralsky grown Pd1−xNix for four Ni-concentrations near xc. Only the lowest Ni-concentration has crystallized as a single crystal, while the higher concentrations remained polycrystalline. For large values of x the typical behavior of a weakly ferromagnetic metal akin stoichiometric compounds like Ni3Al, YNi3 or ZrZn2 is observed. In contrast, for low concentrations two regimes may be distinguished. Moreover, an analysis of the mode-mode coupling as inferred from the magnetic field dependence of the magnetization suggests that the it stays positive for all x as expected of quantum criticality. But the concentration dependence of the spontaneous moment indicates that Pd1−xNix stays ferromagnetic on local scales even for very small concentrations. This suggests that quantum criticality in Pd1−xNix is more complex then previously thought.

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