Berlin 2005 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 12: Correlated Electrons - Spin Systems and Itinerant Magnets: Experiment

TT 12.1: Vortrag

Samstag, 5. März 2005, 10:45–11:00, TU H2053

Small Angle Neutron Scattering Study of the Magnetic Phase Diagram of MnSi at High Pressure — •C. Pfleiderer^1,2, D. Reznik^2,3, L. Pintschovius², and H. v. Löhneysen^1,2 — ¹Physikalisches Institut, Wolfgang-Gaede Str. 1, D-76128 Karlsruhe, Germany — ²Forschungszentrum Karlsruhe, Institut für Festkörperphysik, D-76021 Karlsruhe, Germany — ³Laboratoire Leon Brillouin, CEA Saclay, F-91191 Gif-sur-Yvette Cedex, France

The electrical resistivity of the itinerant-electron magnet MnSi suggests as function of pressure an abrupt change from a Fermi liquid to an extended non-Fermi liquid phase above p_c=14.6 kbar. Recently we reported the existence of partial magnetic order in a small pocket of the regime of the non-Fermi liquid phase, where the partial order is characterised by scattering intensity everywhere on the surface of a small sphere in reciprocal space. Here we report a small angle neutron scattering study of the magnetic state of MnSi at pressures up to 22 kbar and magnetic field up to 1 T. Above the critical pressure long-range helical order may be stabilised in magnetic field, where the pressure dependence of the pinning potential of the helical order and key features of hysteresis loops provide microscopic hints consistent with the formation of a stable new phase.