Seminars & Lectures
| * TITLE | Multiferroics: Magnetism-driven Ferroelectricity | ||||||
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| * DATE / TIME | 2009-06-05, 4:30 p.m. | ||||||
| * PLACE | APCTP Seoul Branch Office | ||||||
| * ABSTRACT | |||||||
| Multiferroics, where magnetic order with broken inversion symmetry accompanies the occurrence of ferroelectric polarization, can show remarkable tunability of dielectric properties by applied magnetic fields, such as reversibly flipping of ferroelectric polarization or a drastic change of dielectric constant with fields. Among such materials, spinel CoCr2O¬4, exhibiting a conical-spiral spin order, is unique in that it exhibits spontaneous magnetization as well as electric polarization. I will present the detailed switching behavior of magnetoelectric domains, characterized by polarization, magnetization, and magnetic wave vector, under variation of temperature and applied magnetic fields. I will also discuss newly-discovered multiferroicity in a \"collinear\" chain magnet of Ca3(Co,Mn)2O6, where the ferroelectricity originates from the coexistence of the alternating order of magnetic ions with different charges and the collinear up-up-down-down spin order in the frustrated spin chain. As a summary, discussion for current efforts toward practical application of multiferroics will be briefly given. Y. J. Choi et al., Phys. Rev. Lett. 102, 067601 (2009) Y. J. Choi et al., Phys. Rev. Lett. 100, 047601 (2008) T. Choi, S. Lee, Y. J. Choi, V. Kiryukhin and S-W. Cheong, Science 324, 63 (2009) |
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