Dynamic magnetoelectric phenomena within electromagnons in rare-earth borate multiferroics
A.A. Mukhina,
A.M. Kuzmenkoa,
V.Yu. Ivanova,
A.G. Pimenovb,
A.M. Shuvaevb,
V.E. Dziomb aProkhorov General Physics Institute of the Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119991, Russian Federation bInstitute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstraße 8-10, Vienna, 1040, Austria
Electroactive spin excitations (electromagnons), an analog of the low-frequency quasiferromagnetic antiferromagnetic resonance (AFMR) mode in a Fe subsystem, are observed in multiferroic rare-earth ferroborates (specifically in SmFe3(BO3)4) in the frequency range of 40—150 GHz, which are shown to contribute dominantly to the giant quasi-static magnetodielectric effect and which produce two types of dynamic magnetoelectric effects: (a) giant optical activity, which occurs for the wave vector k parallel to the crystallographic axis c, k || c, in a transverse magnetic field H || a and which involves polarization plane rotation by more than 70 deg mm−1 in the resonance; and (b) directional birefringence and dichroism in a transverse magnetic field H || b-axis, which show up in radiation transmission asymmetry between the forward k || c) and backward k || c) directions, which is equivalent to the sign change Hb → −Hb. A theory is developed which explains the observed dynamic magnetoelectric phenomena quantitatively by taking into consideration the different symmetry of the tensors of magnetic, magnetoelectric and dielectric susceptibilities for H || a and H || b.
Keywords: magnetoelectric phenomena, multiferroics, magnetic excitations, magnetic spectroscopy, antiferromagnetic resonance PACS:75.85.+t, 76.50.+g, 78.20.Fm (all) DOI:10.3367/UFNe.0185.201510l.1089 URL: https://ufn.ru/en/articles/2015/10/g/ 000367246700006 2-s2.0-84954315043 2015PhyU...58..993M Citation: Mukhin A A, Kuzmenko A M, Ivanov V Yu, Pimenov A G, Shuvaev A M, Dziom V E "Dynamic magnetoelectric phenomena within electromagnons in rare-earth borate multiferroics" Phys. Usp.58 993–1001 (2015)