Dresden 2006 – wissenschaftliches Programm
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MA: Magnetismus
MA 11: Spin-Structures and Magnetic Phase Transitions II
MA 11.4: Vortrag
Montag, 27. März 2006, 15:45–16:00, HSZ 403
Bulk Properties and Neutron Diffraction of the Magnetic Phase Diagram of MnSi — •Daniel Lamago1, Christian Pfleiderer1, Robert Georgii2, and Peter Böni1 — 1Physics Department E21, TU München, D- 85747 Garching, Germany — 2FRM-II, Lichtenbergstr. 1 D-85747 Garching, Germany
MnSi develops itinerant-electron magnetism below TC = 29 K that supports a long wavelength helical modulation. In recent years the properties of MnSi have attracted great scientific interest:[1](i) well above TC chiral magnetic fluctuations have been observed; (2) the magnetic ground state appears to switch abruptly from a weakly spin-polarized Fermi-Liquid to an extended non-Fermi liquid (NFL) phase at a pressure of 14.6 kbar; (3) neutron scattering shows that large magnetic moments survive far into the NFL-phase, where the scattering intensity observed everywhere on the surface of a small sphere suggests partial order analogous to liquid crystals. Motivated by recent efforts [2] we revisit reorientational processes of the helical modulation in MnSi at ambient Pressure as funtion of field. We combine small-angle neutron scattering with AC susceptibility, DC and Torque magnetisation data. This provides unexpected, new insights into the nature of the helical modulation and its possible connection to the NFL phase and the partial magnetic order at high pressure.
[1] B. Roessli et al., Phys. Rev. Lett. 88, 237204 (2002); C. Pfleiderer et al., Nature 414, 427 (2001); N. Doiron-Leyraud et al., Nature 425, 595 (2003); C. Pfleiderer et al., Nature 427, 227 (2004).
[2] A.I. Okorokov et al. Physica B 356, 259 (2005).