Dresden 2020 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

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

KFM 8.1: Talk

Wednesday, March 18, 2020, 09:30–09:45, HSZ 401

High Temperature THz study of conical phase of BiFeO3 — •Dániel Gergely Farkas^{1, 2}, Boglárka Tóth¹, Kirill Amelin³, Toomas Rõõm³, Urmas Nagel³, Toshimitsu Ito⁴, and Sándor Bordács¹ — ¹Department of Physics, Budapest University of Technology and Economics — ²Condensed Matter Research Group of the Hungarian Academy of Sciences, 1111 Budapest, Hungary — ³National Institute of Chemical Physics and Biophysics, Tallinn, Estonia — ⁴National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, Japan

Multiferroics, materials with coexisting ferroelectric and magnetic order, are one of the most intensively studied systems in modern solid-state physics. BiFeO3 is one of the most studied multiferroic material since its multiferroic phase persists also at room temperature [1].

A recent theoretical model [2] predicted a conical phase between the cycloidal and canted AFM phase in BiFeO3. Magnetization measurements up to 300K have already confirmed the existence of this intermediate phase [3].

We performed THz absorption measurements at temperatures between 5-350K, and observed the magnon spectrum of the conical phase. The phase transitions and their hysteresis were observed at 300 and 350K.

[1] J. Moreau, et al., J. Phys. Chem. Solids 32, 1315 (1971).

[2] Z. V. Greeva, et al., Phys. Rev. B 87, 214413 (2013).

[3] S. Kawachi, et al., Phys. Rev. Mat. 1, 024408 (2017).