Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 8: Correlated Electrons: Spin Systems and Itinerant Magnets 1

TT 8.2: Vortrag

Montag, 25. Februar 2008, 14:15–14:30, H 0104

Magnetic phase diagram of MnSi revisited — •Florian Jonietz¹, Sebastian Mühlbauer^1,2, Christian Pfleiderer¹, Achim Rosch³, Rembert Duine⁴, Andreas Neubauer¹, Stefan Legl¹, Robert Georgii^1,2, and Peter Böni¹ — ¹Physik-Department E21, Technische Universität München, D-85748 Garching, Germany — ²Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, D-85748 Garching, Germany — ³Institute of Theoretical Physics, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany — ⁴Institute for Theoretical Physics, Department of Physics and Astronomy, Utrecht University, 3584 CE Utrecht, The Netherlands

The lack of inversion symmetry in the crystal structure of the itinerant-electron magnet MnSi results in weak Dzyaloshinsky-Moriya interactions, that stabilize a long-wavelength spin spiral (λ∼ 190 Å) in the magnetically ordered state. Motivated by recent neutron scattering studies of the magnetic phase diagram at high pressures we have revisited the magnetic phase diagram at ambient pressure. We report the results of extensive measurements of the AC susceptibility and small angle neutron scattering of the magnetic order of MnSi as function of temperature, magnetic field and electric current. In our study we focus in particular on the stability of the A-phase, a small phase pocket, where the helical order spontaneously aligns perpendicular to the direction of an applied magnetic field.