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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 25: Ferroics and Multiferroics (joint session KFM/TT/MA)
KFM 25.9: Talk
Thursday, March 15, 2018, 12:30–12:50, EMH 225
Magnetic Excitations and High-Order Magnetoelectric Effect in Holmium Langasite — •Lukas Weymann1, Thomas Kain1, Alexey Shuvaev1, Artem Kuzmenko2, Alexander Mukhin2, Evan Constable1, Lorenz Bergen1, Nadezhda Kostyuchenko1, Anna Pimenov1, and Andrei Pimenov1 — 1Institute of Solid State Physics, Vienna University of Technology, 1040 Vienna, Austria — 2Prokhorov General Physics Institute, Russian Academy of Sciences, 119991 Moscow, Russia
Recently, compounds of the langasite family (prototype La3Ga5SiO14) have attracted considerable attention due to their intriguing magnetic and magnetoelectric properties. The geometric frustration of the magnetic ions lies in the focus of the investigation of rare-earth langasites, since this makes them promising candidates for spin liquids.
In this work we show that in diluted rare-earth langasite La2.91Ho0.09Ga5SiO14 (3%Ho-LGS), where no magnetic frustration is present, unusual properties can be observed. 3%Ho-LGS single crystals reveal a substantial magnetoelectric effect comparable with other rare-earth langasites. The symmetry and the field dependence of the effect can only be explained by taking into account the higher order expansions of the crystal field theory. Terahertz measurements with a Mach-Zehnder interferometer reveal a series of characteristic magnetic excitations and a strong zero-field mode of presently unknown origin.