Regensburg 2025 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 3: Multiferroics and Magnetoelectric Coupling (joint session MA/KFM)
KFM 3.4: Vortrag
Montag, 17. März 2025, 10:15–10:30, H16
Non-trivial Spin Structures and Multiferroic Properties of the DMI-Compound Ba2CuGe2O7 — •Peter Wild1, Korbinian Fellner1, Michał Dembski-Villalta1, Markus Garst2, Eric Ressouche5, Tommy Kotte3, Bertrand Roessli4, Alexandra Turrini4, and Sebastian Mühlbauer1 — 1Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Garching, Germany — 2Karlsruhe Institute of Technology, (KIT), Karlsruhe, Deutschland — 3Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany — 4Paul Scherrer Institut (PSI), Villigen, Switzerland — 5Institut Laue-Langevin (ILL), Grenoble, France
Antiferromagnetic Ba2CuGe2O7, characterized by a quasi-2D structure with Dzyaloshinskii-Moriya interactions (DMI), is a non-centrosymmetric insulator that exhibits spiral spin structures with potential non-trivial topology and a variety of unconventional magnetic phase transitions. Below the Néel temperature TN = 3.05K, the DMI term leads to a long-range incommensurate, almost AF cycloidal spin spiral in the ground state. Recently, a new phase with a vortex-antivortex magnetic structure has been theoretically described and experimentally confirmed in a pocket in the phase diagram at around 2.4K and an external field along the crystalline c-axis of around 2.2T. A lack of evidence for a thermodynamic phase transition towards the paramagnet in specific heat measurements and a finite linewidth in E and Q of the incommensurate peaks in neutron scattering, as opposed to the cycloidal ground state, seem to mark the vortex phase as a slowly fluctuating structure at the verge of ordering.
Keywords: multiferroics; vortex; incommensurate; DMI; quasi-2D