Seminars & Lectures
| * TITLE | Multifunctional Multiferroics | ||||||
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| * DATE / TIME | 2005-11-28, 3:00 p.m | ||||||
| * PLACE | Seminar Room #512, APCTP Headquarters | ||||||
| * ABSTRACT | |||||||
| Ferroelectric and magnetic materials have been a time-honored subject of study and have led to some of the most important technological advances to date. Magnetism and ferroelectricity are involved with local unpaired spins and local dipoles (originating from off-center structural distortions), respectively. These two seemingly unrelated phenomena can coexist in certain unusual materials, termed multiferroics. Despite the possible coexistence of ferroelectricity and magnetism, a pronounced interplay between these properties has rarely been observed. This has prevented the realization of multiferroic devices offering such functionality. We will discuss newly-discovered, extraordinary coupling between spin and lattice degrees of freedom in a certain class of multiferroics. For example, the highly reproducible electric polarization reversal in TbMn2O5 and TbMnO3 and unprecedented large change of dielectric constant in DyMn2O5 and DyMnO3 can be activated by an applied magnetic field (H). In addition, acoustic phonons in hexagonal-HoMnO3 can be significantly influenced by H. These manifestations of giant spin/lattice coupling provide new device concepts with tunable multifunctionality. |
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