Multiferroics

Abstract

This special issue deals with the simultaneous occurrence of at least two primary ferroic properties, namely of ferroelectricity, ferromagnetism, ferrotoroidicity or ferroelasticity in one single homogeneous phase. The question of how different ferroic states can coexist in a single-phase material is an important issue and is outlined in detail using symmetry arguments and Landau theory for continuous phase transitions, which shows that the spin structure alone can break spatial inversion symmetry leading to ferroelectric order. The main focus of this special issue lies on single-phase materials that are magnetic and ferroelectric. They promise control of electric properties by magnetic fields and the control of magnetic properties by electric fields. The magnetoelectric coupling will allow the design of materials with novel electronic properties and in selected cases bring them to application.