Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique
TT 16.1: Poster
Samstag, 5. März 2005, 11:00–16:30, Poster TU C
Quantum Criticality in the frustrated Laves phase compound NbFe2 — •Dennis Moroni-Klementowicz, Manuel Brando, and Friedrich Malte Grosche — Department of Physics, Royal Holloway, University of London, Egham, TW20 OEX, United Kingdom
Geometric frustration in nearly magnetic metals provides a promising and relatively little explored path to obtaining high electronic density of states - hatching condition of novel quantum order. Various compounds close to the border of magnetism can be found amongst intermetallic C14 and C15 Laves phases. We have focused on one of the most interesting examples: NbFe2. Depending on precise stoichiometry, pressure and applied magnetic field, NbFe2 can be tuned between ferromagnetic, antiferromagnetic and enhanced paramagnetic low temperature states. Because stoichiometry and annealing are crucial in this compound we have put particular effort in making high quality samples using cold crucible RF heating techniques, extended annealing close to the melting point and zone refining, as well as detailed characterisation by heat capacity and magnetisation measurements. The complex phase diagram of NbFe2 gives rise to several regions in which an ordering temperature is suppressed to low temperatures. We investigate the vicinity of these quantum critical points by high sensitivity measurements of the electrical resistivity under applied magnetic fields and high hydrostatic pressure, as well as ambient pressure heat capacity measurements, down to the sub-100 mK range.