KIAS- APCTP Workshop on "Quantum Materials"
at Korea Institute for Advanced Study (KIAS), Seoul, Korea
July 19(Wed)-22(Sat), 2006
Title | New Magnetic Twists for Ferroelectricity |
Abstract | Extraordinary cross-coupling effects between magnetism and dielectric properties have been recently observed in multiferroics where magnetic and ferroelectric orders coexist. 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 applied magnetic fields (H). In addition, acoustic phonons in hexagonalÐHoMnO3 can be significantly influenced by H. It turns out that the ferroelectricity in those multiferroics arises from non-colinear magnetic orders with inversion symmetry broken, originating from with magnetic frustration. Examples of the non-colinear magnetic orders include spiral (twist) magnetic orders. Role of spin-orbital coupling and exchange-striction on the cross-coupling effects will be discussed. |