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TT: Fachverband Tiefe Temperaturen

TT 16: CE: Quantum-Critical Phenomena 1

TT 16.8: Vortrag

Dienstag, 23. März 2010, 15:45–16:00, H19

Low temperature properties of single crystal Fe₂TiSn under high pressure and magnetic field — •Andreas Neubauer¹, Michael Schulz^1,2, Christian Pfleiderer¹, Peter Böni¹, Klaudia Hradil², and Günther Behr³ — ¹Physik Department E21, Technische Universität München, 85748 Garching, Germany — ²Technische Universität München, Forschungsneutronenquelle Heinz Maier Leibnitz (FRM II),Lichtenbergstr. 1, 85748 Garching, Germany — ³Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, PF270116, 01171 Dresden, Germany

Electronic structure calculations predict a paramagnetic ground state for the Heusler compound Fe₂TiSn. However, the experimental investigation of polycrystals showed weakly ferromagnetic behaviour (T_C∼250 K), where the magnetic properties are extremely sensitive to sample synthesis. We were able to grow, for the first time, single crystals of Fe₂TiSn by the optical float zoning using an UHV-compatible image furnace. The inverse AC susceptibility of the single crystals shows a paramagnetic Curie-Weiss-behaviour from room temperature down to around 5K, followed by a transition to a so far unidentified phase. Interestingly, the inverse susceptibility extrapolates through T=0, a behaviour expected for ferromagnetic quantum criticality. We investigated the pressure dependence of the magnetization, the longitudinal magneto-resistance and the Hall effect. These data are supplemented by neutron depolarization measurements. Possible implications of our observations for the possible nature of quantum criticality in Fe₂TiSn will be discussed.