Condensed Matter Physics Seminar
2 p.m., Thursday, September 28, 2006
Room 1201, Physics Building
Improper Ferroelectrics as new Magnetoelectric Materials
(Oak Ridge National Laboratory)
Abstract: A stunning magnetoelectric effect - the switching of
electric polarization by magnetic field was reported in TbMnO3 and
TbMn2O5 a few years ago [1,2]. A large number of related
materials has been discovered since then. It is now understood that while there
is no intrinsic ferroelectric instability in these compounds, the polarization
appears due to its coupling to exotic magnetic order parameters that break
inversion symmetry. Correspondingly, the polarization is sensitive to the
field-induced magnetic phase transitions. I will discuss the possible
microscopic mechanisms underlying magnetoelectric coupling in improper
ferroelectrics and ways to enhance their ferroelectric properties, with the
primary focus on perovskite manganites [3,4].
 T. Kimura et al., Nature 426, 55, (2003).
 N. Hur et al., Nature 429, 392, (2004).
 I.A. Sergienko and E. Dagotto, Phys. Rev. B 73, 094434 (2006).
 I.A. Sergienko, C. Sen, and E. Dagotto, cond-mat/0608025.
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