Dresden 2014 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 35: Correlated Electrons: Quantum-Critical Phenomena - Experiment I
TT 35.9: Vortrag
Dienstag, 1. April 2014, 11:45–12:00, HSZ 204
Competing order parameters in NbFe2 — •Sven Friedemann1, Max Hirschberger1,2, William J Duncan1, Andreas Neubauer2, Thomas Bauer3, Manuel Brando3, Christian Pfleiderer2, and F Malte Grosche1 — 1Cavendish Laboratory, University of Cambridge, Cambridge, UK — 2Physik Department E21, TU München, Garching, Germany — 3Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
Quantum criticality in transition metal compounds imposes long-standing challenges:
Near the border of magnetism at low temperature, T, prominent examples like the ferromagnets MnSi and ZrZn2 obey unconventional power law-dependencies of the resistivity which cannot be understood within the standard magnetic fluctuation theory.
Here, we present new results on NbFe2 in which a T3/2 dependence of the resistivity has also been observed [1]. NbFe2 can be tuned by varying the composition, thus enabling detailed investigations not possible in pressure tuned systems. While slightly iron-rich samples are ferromagnetic at low T<Tc, Tc is suppressed to 0 on approaching stoichiometry and a new phase is observed above Tc.
Using high-purity single crystals we conduct comprehensive studies of bulk magnetic, thermodynamic, and transport properties. These prove the presence of both ordered states. We show that our results are consistent with the competing order parameter theory of uniform and modulated magnetic states as proposed by Moriya and Usami [2]. We infer that the quantum critical behaviour in NbFe2 is associated with the modulated magnetic order.
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