Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 41: Correlated Electrons: Quantum-Critical Phenomena
TT 41.9: Talk
Wednesday, March 22, 2017, 11:45–12:00, HSZ 204
Quantum Tricritical Points in NbFe2 — •Sven Friedemann1,2, Max Hirschberger2,4, Thomas Bauer3, Robert Kuechler3, Andreas Neubauer4, Manuel Brando3, Christian Pfleiderer4, and F Malte Grosche2 — 1HH Wills Laboratory, University of Bristol, UK — 2Cavendish Laboratory, University of Cambridge, Cambridge, UK — 3Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — 4Physik Department E21, TU München, Garching, Germany
Quantum critical points (QCPs) in ferromagnetic (FM) metals impose a long-standing challenge including seemingly incompatible temperature dependencies in transport and thermodynamic properties. In many of these systems, the FM QCP is avoided through a change to 1st order. Here, we present results on a second class of FM quantum critical metals in which the QCP is avoided through an intervening spin-density-wave (SDW) phase. We show that the phase diagram of NbFe2 can be modelled with a two-order-parameter theory in which the FM QCP is buried within a SDW phase, as proposed by Moriya and Usami [1]. This model reproduces detailed magnetisation measurements on high-purity single crystals for a series of samples tuned across the buried FM QCP via variations in the composition. We establish the presence of quantum tricritical points at which both the uniform and finite wavelength susceptibility diverge, which may explain the incompatible temperature dependencies.
Sol State Com, 23 935 (1977)