Dresden 2017 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 18: Multiferroics (DF and MA)
DF 18.7: Vortrag
Donnerstag, 23. März 2017, 16:45–17:00, WIL B321
Magnetic excitations in multiferroic GdMn2O5 — •Sergey Poghosyan and Sergey Artykhin — Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
RMn2O5 compounds recently attracted attention due to non-collinear states and unconventional excitations. YMn2O5 with non-magnetic rare earth (RE) shows incommensurate spiral state with spins in the neighbouring chains aligned at 90-degrees to each other [1]. RE ions with unquenched angular momentum enable the control of polarization by magnetic field in the multiferroic materials, such as TbMn2O5 [2]. GdMn2O5 with magnetic rare earth in S=7/2, L=0 state, exhibits a spiral state below 40 K, that concedes to a commensurate state below ∼30K. The latter hosts large magnetically-induced polarization of 3600 µ C/m2 induced via Heisenberg exchange striction mechanism. This polarization changes by 5000 µ C/m2 under the external magnetic field [3]. Here we corroborate THz magnetoabsorption data with the microscopic modelling. The magnetic excitations are calculated using model Hamiltonian with parameters extracted from ab-initio simulations. The resultant magnon spectrum is rather counterintuitive and complex, thus providing new insights on design principles for materials with strong magnetoelectric couplings.
[1] J.-H. Kim et al., Phys. Rev. Lett. 107, 097401 (2011).
[2] N. Hur et al., Nature 429, 392 (2004).
[3] N. Lee et al., Phys. Rev. Lett. 110, 137203 (2013).