Berlin 2018 – scientific programme

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MA: Fachverband Magnetismus

MA 45: Ferroics and Multiferroics (joint session KFM/TT/MA)

MA 45.9: 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 La_2.91Ho_0.09Ga₅SiO₁₄ (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.