Berlin 2008 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 6: Correlated Electrons: Heavy Fermions
TT 6.4: Talk
Monday, February 25, 2008, 10:15–10:30, EB 202
Magnetoresistance and anomalous Hall effect in ferromagnetic CeSi1.81 — •Robert Ritz1, Andreas Neubauer1, Stefan Legl1, Christian Pfleiderer1, Dmitri Souptel2, and Günter Behr2 — 1Physik-Department E21, Technische Universität München, D-85748 Garching, Germany — 2Leibniz-Institut für Festkörper-und Werkstoffforschung(IFW) Dresden, P.O. Box 270116, D-01171 Dresden, Germany
As function of Si content the series CeSix changes from an antiferromagnetic ground state for x=1 to paramagnetism for x=2. An abrupt magnetic to non-magnetic transition is observed just below x=2, where single crystals with x=1.81 exhibit an essentially ferromagnetic ground state below TC≈9.5 K that vanishes rapidly under pressure [1]. We report a comparison of the low-temperature magnetoresistance and anomalous Hall effect in CeSi1.81 with the uniform magnetization and specific heat. The longitudinal magnetoresistance suggests the additional formation of a density wave below Tx≈ 3 K. We also find that the spontaneous anomalous Hall effect initially tracks the ordered moment, where deviations below ∼ TC/2 suggests the emergence of additional magnetic modulations. Well below TC a small hysteresis in the Hall effect exists up to Bm ∼ 4 T, the location of an S-shaped increase in the magnetization that is naively interpreted as itinerant metamagnetism. This may hint at a novel interplay between itinerant metamagnetism and structural defects. [1] S. Drotziger, et al., Phys. Rev. B 73, 214413 (2006).