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MA: Fachverband Magnetismus

MA 48: SKM-SYDT: Diffusionless Transformations in Magnetic and Ferroelectric Bulk and Thin Films (jointly with MM, DS, DF)

MA 48.1: Hauptvortrag

Donnerstag, 17. März 2011, 10:30–11:00, TRE Ma

Domain boundaries as active elements in multiferroics and martensites: steps towards Domain Boundary Engineering — •Ekhard K.H. Salje — University of Cambridge, Cambridge CB2 3EQ, UK

Domain boundaries can contain properties, which are absent in the bulk of the material. Typical examples which can be used for applications in Domain Boundary Engineering are ferroelectric boundaries in ferroelastic matrices. A similar example is piezoelectricity in boundaries where the matrix remains non-piezolelectric and materials with reversed contrast. In addition, electronic and ionic transport are often greatly enhanced in boundaries. An extreme case are superconducting twin walls in a ferroelectric matrix. Increased ionic transport is common in twin boundaries of most materials with perovskite-type structures. While much progress has been made in ceramics, we also find indications for specific domain boundary effects in shape memory metals. The mobility of matensitic twins depends greatly on their internal structure, e.g. their ability to anchor dislocations. All materials have in common that strain interactions are strong and hence long correlations prevail. This make the system amenable to Landau theory including appropriate coupling terms which modify the bulk and the domain walls differently. The general concept and some examples will be discussed.

Ref.: E.K.H. Salje (2010) Multiferroic domain boundaries as active memory devices: trajectories towards domain boundary engineering, Chemphyschem 11, 940.