Berlin 2012 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 5: Spin Structures and Magnetic Phase Transitions
MA 5.1: Vortrag
Montag, 26. März 2012, 09:30–09:45, H 0112
Structure and Phase Transitions of the Spiral Antiferromagnet Ba2CuGe2O7 in Canted Magnetic Fields — •Sebastian Mühlbauer1, Severian Gvasaliya1, Eric Ressouche2, Ekaterina Pomjakushina3, and Andrey Zheludev1 — 1Neutron Scattering and Magnetism Group, Laboratory for Solid State Physics, ETH Zürich, Switzerland — 2INAC/SPSMS-MDN, CEA/Grenoble, 38054 Grenoble Cedex 9, France — 3Laboratory for Developments and Methods (LDM), Paul Scherrer Institute, Switzerland
Neutron diffraction in combination with measurements of the 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. For magnetic field close to the tetragonal c-axis, a phase transition from the soliton lattice to a recently reported incommensurate double-k AF-cone phase [1] is confirmed. In contrast, for large angles enclosed by the magnetic field and the c-axis, a smooth crossover to a complexly distorted non-sinusoidal structure is observed by neutron diffraction. Measurements of susceptibility and specific heat furthermore indicate the existence of a incommensurate/commensurate transition for magnetic fields ≈ 9 T applied in the basal (a,b)-plane. The results show a virtually identical behavior for the magnetic field confined in both a (1,0,0) and (1,1,0) crystallographic plane and agree with a non-planar, asymmetrically distorted cycloidal magnetic structure.
[1] S. Mühlbauer et al., Phys. Rev. B 84, 180406 (2011)