Dresden 2009 – wissenschaftliches Programm
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-Elmeguid3 — 1Diamond 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 . 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.
 P. Pedrazzini et al., Phys. Rev. Lett. 98, 047204 (2007).