Raman scattering on multiferroic TbMnO3
Australian Institute of Physics
Multiferroic materials are promising for their technological potential in next-generation microelectronics. They are materials that possess coexisting ferroelectric polarisation and magnetic order, and in particular cases they exhibit coupling between these parameters. This offers the possibility of manipulating ferroelectric polarisation via magnetic order and vice versa, leading to low-powered, ultra-high-capacity solid-state memory or sensor applications. At present, the physics that underpin magnetoelectric coupling in multiferroics is not entirely understood. Competing theories exist that propose different experimental outcomes. In studying the nature of excitations via Raman scattering, this research intends to provide deeper insight into such behaviour in TbMnO3 and for multiferroic materials in general. We have performed Raman spectroscopy measurements on a TbMnO3 crystal and two oxygen-isotope-substituted powder samples. Anomalies in oxygen-octohedra stretching modes have been examined in respect to the sinusoidal and multiferroic phases in this material. Anomalies at TC ~28 K may be ascribed to spin-phonon coupling or to other effects related to the coupled cycloidal-spin and ferroelectric order in the multiferroic phase. Results for anomalies between oxygen-isotope substituted samples indicate that the physical origin for these anomalies is sensitive to oxygen mass. If spin-phonon coupling is responsible for anomalies in the multiferroic phase, our results may suggest that the Dzyaloshinskii-Moriya model, as opposed to the spin-current model, more correctly describes magnetoelectric coupling in TbMnO3. Further experimental and theoretical work is in preparation to explore the implications of our results for magnetoelectric coupling in this material.
Raman spectroscopy, Terbium, Manganese, Materials, Polarization, Electrical properties, Spin, Coupling
Graham, P. J., Bartowiak, M., Mulders, A. M., Yethiraj, M., Pomjakushina, E., & Urlich, C. (2012). Raman scattering on multiferroic TbMnO3. Poster presented to the 36th Annual Condensed Matter and Materials Meeting, Wagga 2012, Charles Sturt University, Wagga Wagga, NSW 31st January – 3rd February, 2012. Retrieved from: https://physics.org.au/wp-content/uploads/cmm/2012/