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TT: Fachverband Tiefe Temperaturen

TT 14: Spin Systems and Itinerant Magnets

TT 14.2: Vortrag

Dienstag, 27. März 2007, 14:15–14:30, H19

Hall effect and magnetoresistance in weakly ferromagnetic CeSi_x and heli-magnetic MnSi — Andreas Neubauer¹, Christian Pfleiderer¹, Philipp Niklowitz¹, Robert Ritz¹, •Peter Böni¹, Dmitri Souptel², and Günter Behr² — ¹Physik Department E21, Technische Universität München, D-85748 Garching, Germany — ²IFW Dresden, PF 270116, D-01171, Dresden, Germany

We report a comparison of the magnetoresistance and Hall effect in single crystals of the easy-plane ferromagnet CeSi_x (x≈1.81) with that observed in the helical magnet MnSi. In CeSi_x the anomalous Hall effect clearly tracks the ordered moment as function of temperature and magnetic field. It may be used as a simple means to establish the presence of a ferromagnetic quantum phase transition under pressure. The behavior seen in ferromagnets CeSi_x is contrasted by anomalous contributions to the Hall effect in MnSi, which suggest an important scale of order 100K. Further, in MnSi only subtle differences in the temperature dependences of the Hall effect near a quantum phase transition may be expected. We compare a conventional analysis in the framework of additive charge carrier relaxation rates with the more recent proposal of additive currents.