Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 28: Correlated Electrons: Spin Systems, Itinerant Magnets 3
TT 28.1: Vortrag
Dienstag, 12. März 2013, 09:30–09:45, H19
Structure and Phase Transitions of the Spiral Antiferromagnet Ba2CuGe2O7 — •Sebastian Mühlbauer1, Markus Garst2, Ekaterina Pomjakushina3, Severian Gvasaliya4, Eric Ressouche5, Charles Dewhurst5, Joachim Kohlbrecher3, and Andrey Zheludev4 — 1Forschungsneutronenquelle Heinz Maier-Leibnitz, Garching, Germany — 2Institut für Theoretische Physik, Universität zu Köln, Germany — 3Paul Scherrer Institut, Villigen, Switzerland — 4Neutron Scattering and Magnetism, ETH Zürich, Switzerland — 5Institut Laue Langevin, Grenoble, France
Neutron diffraction and small angle neutron scattering (SANS) in combination with measurements of susceptibility and specific heat have been used to systematically study the different magnetic structures of the non-centrosymmetric tetragonal antiferromagnet (AF) Ba2CuGe2O7, that evolve for different orientation of the magnetic field. A complete description of the magnetic phase diagram could be achieved [1,2]: For magnetic field close to the tetragonal c-axis, a phase transition from the soliton lattice to a recently reported incommesurate double-k-phase is confirmed. In contrast, for large angles enclosed by the magnetic field and the c-axis, a complexly distorted non-sinusoidal structure is observed. For magnetic field in the basal a,b-plane, a incommensurate/commensurate transition is observed at 9 T. The staggered component of the Dzyaloshinsky-Moriya vector is identified as key element for the understanding of Ba2CuGe2O7.
[1] S. Mühlbauer et al., Phys. Rev. B 84, 180406 (2011).
S. Mühlbauer at al., Phys. Rev. B 86 02217 (2012).