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TUT: Tutorien

TUT 1: Tutorial on Multiferroics and Magnetoelectrics

TUT 1.2: Tutorium

Sonntag, 22. März 2009, 16:50–17:35, HSZ 401

Magnetoelectric coupling in multiferroics: Recent developments — •Manfred Fiebig — HISKP, Universität Bonn, Bonn, Germany

Currently, an enormous interest in multiferroics – compounds uniting two or more forms of primary ferroic ordering in one phase – is observed. Aside from technological aspects the interplay of different forms of (anti-) ferroic ordering is a rich source for exploring the fundamental science of phase control. Magnetic ferroelectrics may constitute the most interesting type of multiferroics because they may exhibit an unusually strong, so-called magnetoelectric (ME), coupling of magnetic and electric properties which is useful for controlling magnetic order with electric fields and vice versa. In my talk I will discuss the intricate relation between multiferroicity, ME behavior, and symmetry in ME single-phase multiferroics with particular emphasis on recent developments. For example, simultaneous breaking of time- and space-inversion symmetry by magnetic spirals leads to a new type of “induced” ME multiferroic observed, e.g., in orthorhombic RMnO₃, pyroxenes, or MnWO₄. This has to be distinguished from multiferroicity in the popular compound BiFeO₃ which also forms spin-spirals, but independent of the ferroelectric order. On the other hand, space-time asymmetry can also lead to ferrotoroidicity (a spontaneous order of magnetic vortices) as an entirely different form of ferroic ordering observed, e.g., in LiCoPO₄.