Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 17: Correlated Electrons: Quantum-Critical Phenomena 1

TT 17.5: Vortrag

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

Evidence for Unusual Magnetic Order in Cubic FeGe beyond its Quantum Phase Transition — •Heribert Wilhelm1, Alessandro Barla2, Martin Forthaus3, Rudolf Rueffer4, Marcus Schmidt5, and Mohsen Abd-Elmeguid31Diamond Light Source Ltd, Chilton, OX11 0DE, UK — 2Experiments Division, CELLS-ALBA, E-08193 Bellaterra, Barcelona, Spain — 3II. Physikalisches Institut, Universität zu Köln, 50937 Köln — 4European Synchrotron Radiation Facility, BP220, F-38043 Grenoble, France — 5Max Planck Institut für Chemische Physik fester Stoffe, 01187 Dresden

Transport measurements on the cubic modification of FeGe under high pressure have shown that the long-wavelength helical order (TC=280K, at p=0) is suppressed at a critical pressure pc≈ 19GPa [1]. The metallic ground state persisting above pc can be described by band-structure calculations if zero-point motion is included. However, the electrical resistivity shows that the ground state can not be described by Fermi-liquid theory in a wide pressure range above pc. This non-Fermi liquid behavior suggests that the phase transition occurs without quantum criticality. New information based on nuclear forward scattering measurements (p<25GPa, T>3K) revealed a finite but disordered magnetic moment above pc and low temperature. The implication of this finding to the metallic ground state and an updated phase diagram will be discussed.

[1] P. Pedrazzini et al., Phys. Rev. Lett. 98, 047204 (2007).

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