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Why are there so few magnetic ferroelectrics?


Multiferroic magnetoelectrics are materials that are both ferromagnetic  and ferroelectric in the same phase. As a result they have a spontaneous  magnetization which can be switched by an applied magnetic field,  a spontaneous polarization which can be switched  by an applied electric  field, and often some coupling between the two. Very few exist in nature,  or have been synthesized in the laboratory, but there is some incentive  to produce new multiferroics for technological applications.
In this talk we use the study of multiferroics to illustrate  the utility of theoretical and computational methods  in the design of new multifunctional materials.  First we determine the fundamental physics behind the scarcity of  ferromagnetic ferroelectric coexistence, and show that in general  transition metal d electrons, which are essential for magnetism,  reduce the tendency for off-center ferroelectric distortion. Then we  identify the chemistry behind the additional electronic or structural  driving forces that must be present for ferromagnetism and ferroelectricity  to occur simultaneously. Finally we describe the successful prediction and  subsequent synthesis of new multiferroic materials.

Hosts:  John Wei and Young-June Kim