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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 8: Multiferroics and Magnetoelectric Coupling I (joint session MA/KFM)

KFM 8.2: Vortrag

Mittwoch, 18. März 2020, 09:45–10:00, HSZ 401

Metastable transverse conical state in multiferroic BiFeO3 — •Boglarka Toth¹, Daniel Gergely Farkas¹, Jonathan S. White², Istvan Kezsmarki³, Toshimitsu Ito⁴, and Sandor Bordacs¹ — ¹Budapest University of Technology and Economics, Physics Department — ²Paul Scherrer Institute — ³University of Augsburg — ⁴National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8562 Ibaraki, Japan

Magnetoelectric multiferroic materials with coexisting ferroelectric and magnetic orders have received much attention as they may find applications in low power consumption magnetoelectric memories and data storage devices. Among these materials, BiFeO₃ is a unique compound as it is multiferroic even at room temperature, which is essential for future applications. Although BiFeO₃ is the most studied multiferroic material, its magnetic phase diagram is not fully understood. Due to the ferroelectric distortion, the so-called Dzyaloshinskii-Moriya interaction is allowed, which, competing with the Heisenberg interaction, results in a cycloidal structure below T_N = 640 K in zero field. We investigated the magnetic phases above room temperature using magnetization measurements and small-angle neutron scattering (SANS) and found a transverse conical state between the zero-field cycloidal state and the high field canted antiferromagnetic phase. Furthermore, the conical state with large magnetoelectric effect remains (meta)stable in zero-field after decreasing the magnetic field.