THz and infrared studies of multiferroic hexagonal Y.sub.1-x./sub.Eu.sub.x./sub.MnO.sub.3./sub. (x = 0 - 0.2) ceramics

0353097 - FZÚ 2011 RIV GB eng J - Journal Article
Goian, Veronica - Kamba, Stanislav - Kadlec, Christelle - Nuzhnyy, Dmitry - Kužel, Petr - Moreira, J.A. - Almeida, A. - Tavares, P.B.
THz and infrared studies of multiferroic hexagonal Y_1-xEu_xMnO₃ (x = 0 - 0.2) ceramics.
Phase Transitions. Roč. 83, 10-11 (2010), s. 931-941. ISSN 0141-1594. E-ISSN 1029-0338
R&D Projects: GA ČR(CZ) GA202/09/0682
Institutional research plan: CEZ:AV0Z10100520
Keywords : multiferroics * infrared and THz spectroscopy * phonons
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 1.006, year: 2010

We report an investigation of hexagonal Y1-xEuxMnO3 ceramics with x=0, 0.1 and 0.2 using infrared and THz spectroscopies in the temperature range between 5 and 900 K. The temperature dependence of the THz permittivity reveals a kink near the antiferromagnetic phase transition temperature TN  70 K giving evidence of a strong spin-lattice coupling. Below TN two absorption peaks were revealed in the THz spectra close to 43 and 73 cm-1. While the first peak corresponds to a sharp antiferromagnetic resonance exhibiting softening on heating towards TN, the second one may be attributed to an impurity mode or a multiphonon absorption peak. High-temperature THz spectra measured up to 900 K reveal only small gradual increase of the permittivity in agreement with a weak phonon softening observed in the infrared reflectance spectra upon heating. This corresponds to an improper ferroelectric character of the phase transition proposed from first principle calculations by Fennie and Rabe.
Permanent Link: http://hdl.handle.net/11104/0192437