Regensburg 2002 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 3: Schwere Fermionen, Kondo-Systeme I
TT 3.1: Vortrag
Montag, 11. März 2002, 09:30–09:45, H18
Transport properties of disordered strongly correlated uranium compounds — •S. Süllow1, I. Maksimov1, M.B. Maple2, A.A. Menovsky3, and J.A. Mydosh3 — 1Inst. f. Metallphysik, TU Braunschweig — 2University of California-San Diego, USA — 3Leiden University, Leiden, Netherlands
The effect of moderate levels of crystallographic disorder on the physical properties of heavy fermion systems is strongly enhanced compared to normal metals. For instance, this has been demonstrated for URh2Ge2, where spin glass behavior induced by atomic scale disorder is observed. Via an annealing treatment (reducing the disorder level) the nature of the magnetic ground state can be tuned from a spin glass to a long-range ordered antiferromagnetic one. The transformation of the magnetic ground state is accompanied by a transition in the transport properties from ”quasi-insulating” (dρ/dT<0 below room temperature) to metallic. Surprisingly, the transport properties of spin glass URh2Ge2 closely resemble that of UCu4Pd, for which Cu/Pd disorder had been established. For the latter system the resistivity had been taken as evidence for NFL behavior. However, the similarity to URh2Ge2 suggests that it is rather the crystallographic disorder than the vicinity to a magnetic instability that controls the transport properties of these materials. We will discuss the disorder phase diagram of these uranium compound, and the different role disorder plays regarding the magnetic ground state and transport properties, respectively.
Work supported by DFG, NSF and FOM-ALMOS.