Abstract
The interplay between magnetism and electricity in matter has become a central issue of condensed-matter physics. Here I focus on the ferroelectricity induced by magnetic order mostly in frustrated magnets, which is nowadays referred to as magneto-electric (ME) multiferroic. Some distinct types of microscopic origins relevant to the spin-driven ferroelectricity are discussed. It is also shown that the frustration based spin-driven ferroelectrics can exhibit nonlinear and giant ME responses of phase transition type.
