Multiferroics

A multiferroic material in general is defined by the coexistence of two coupled ferroic ordering parameters - typically ferroelectricity and magnetism. Such materials are highly intersting from the fundamental point of view as well as for applications. For example one can apply an eletric field and switch the magnetic state - which would allow for much smaller read-write heads in data storage devices.

Visualization of ferroelectric domains in manganites
In collaboration with Manfred Fiebig, HISKP University of Bonn

Piezoresponse force microscopy allows for the detectio of ferroelectric fomain patterns with an astonishingly high sensitivity together with a high lateral resolution of ~ 10 nm. We investigated the domain pattern in YMnO₃ and HoMnO₃ thereby detecting the domain pattern on all faces of the crystals. Surprisingly the kaleidoscopic topology could be found irrespective of the face investigated - see figure below.