The interplay between electricity and magnetism has fascinated scientists and engineers for centuries, ever since Hans Christian Oersted noticed in 1820, quite by accident, that a magnetic compass needle deflected when he switched the current in a nearby battery on or off. Over the 40 years or so following Oersted’s observation, the classical theory of electromagnetism was worked out, with seminal contributions from the likes of André Marie Ampère and Michael Faraday; that work culminated in the 1860s with James Maxwell’s unified theory. The implications of those discoveries for society need no elaboration. This article focuses on how electricity and magnetism interplay in a class of real materials—the multiferroics—in which spontaneous magnetic and dielectric ordering occur.
Over the past few years, the field has evolved rapidly; many of the materials science and solid-state chemistry issues that once plagued sample quality have been resolved, and genuine physical effects can be studied.