Raman scattering studies of hexagonal rare-earth RMnO3 (R = Tb, Dy, Ho, Er) thin films

• Published in: Journal of Raman spectroscopy 2011-09, Vol.42 (9), p.1774-1779
• Main Authors: Hien, Nguyen Thi Minh, Oh, Su-Young, Chen, Xiang-Bai, Lee, D., Jang, S.-Y., Noh, T. W., Yang, In-Sang
• Format: Article
• Language: English
• Subjects: Dysprosium; Erbium; hexagonal RMnO3; Lattice parameters; magnon scattering; Magnons; Néel temperature; phonon scattering; Phonons; Rare earth metals; Spin waves; spin-exchange integral; Thin films
• ISSN: 0377-0486; 1097-4555; 1097-4555
• DOI: 10.1002/jrs.2925

We have studied the rare‐earth (R) dependence of the phonon and magnon scattering in hexagonal RMnO3 (R = Tb, Dy, Ho, Er) thin films using Raman scattering spectroscopy. We found, as the ionic radius of R decreases from Tb to Er, the phonons shift to higher energies. Our results indicate that both the lattice constants a and c of hexagonal RMnO3 would decrease when the ionic radius of R decreases, and the lattice constant c would have a weaker R dependence. The magnons also shift to higher energies when the radius of the R ion decreases, and they show faster upshift than the phonons. In addition, the Néel temperature also shows a systematic increasing behavior when the radius of the R ion decreases. The dependence of the rare‐earth R on the magnons and the Néel temperature can be explained by the rapid increase of the spin‐exchange integral when the Mn–Mn distance decreases. Copyright © 2011 John Wiley & Sons, Ltd. We have studied the rare‐earth R dependence of the phonon and magnon scattering in hexagonal RMnO3 (R = Tb, Dy, Ho, Er) thin films using Raman scattering spectroscopy. We found, as the R ionic radius decreases from Tb to Er, the phonons shift to higher energies. Our results indicate that both the lattice constants a and c of hexagonal RMnO3 would decrease when the R ionic radius decreases, and the lattice constant c would have a weaker R dependence. The magnons also shift to higher energies when the radius of the R ion decreases, and they show faster upshift than the phonons. In addition, the Néel temperature also shows a systematic increase when the radius of the R ion decreases. The rare‐earth R dependence of the magnons and the Néel temperature can be explained by the rapid increase of the spin‐exchange integral when the Mn‐Mn distance decreases.