Evidence for Unusual Magnetic Order in Cubic FeGe beyond its Quantum Phase Transition

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• Heribert Wilhelm, University of Geneva, Switzerland and Diamond Light Source
• Wednesday 25 November 2009, 11:15-12:15
• Mott Seminar Room, Cavendish Laboratory, Department of Physics.

If you have a question about this talk, please contact Michael Sutherland.

Transport measurements on the cubic modification of FeGe under high pressure have shown that the long-wavelength helical order (T_C=280K, at p=0) is suppressed at a critical pressure p_c~19GPa [1]. The metallic ground state persisting above p_c 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 p_c. This non-Fermi liquid behavior suggests that the phase transition occurs without quantum criticality. New information based on nuclear forward scattering measurements (p 3 K) revealed a finite but disordered magnetic moment above p_c 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).

This talk is part of the Quantum Matter Seminar series.

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