WFD-5 　 Giant spin/lattice coupling in multiferroics S. Cheong Department of Physics & Astronomy, Rutgers University, 136 Frelinghuysen Rd. Piscataway, NJ 08854, USA 　　　　Ferroelectric and magnetic materials have been a time-honored subject of study and 　　　　have lead to some of the most important technological advances to date. Magnetic 　　　　ordering is governed by the exchange interaction of the electron spins, while 　　　　ferroelectric ordering is governed by the off-center structural distortions in the 　　　　lattice. These two seemingly unrelated phenomena can actually coexist in certain 　　　　unusual materials, termed multiferroics. The understanding of this remarkable 　　　　occurrence remains a scientific challenge. Despite the possible coexistence of 　　　　ferroelectricity and magnetism, any profound interplay between them has been rarely 　　　　observed. This fact has largely prevented the realization of devices with apreviously 　　　　unavailable functionality, which these multiferroics could make possible. We have 　　　　recently discovered astonishing interplays between ferroelectricity and magnetism 　　　　demonstrated by polarization reversal by magnetic fields as well as colossal 　　　　magneto-capacitance effect in REMn2O5 (RE: rare earth). Our findings point to new 　　　　device applications such as magnetically recorded ferroelectric memory and important 　　　　means to tune dielectric properties with external parameters.