Multiferroic compounds are materials which show several order parameters including for instance ferroelectricity and magnetism. The coupling between these two orders is an important property called magnetoelectric coupling leading to exciting potential applications in information technology and sensors. Bismuth ferrite (BiFeO3) is the only multiferroic with both ordering temperatures way above room temperature, but unfortunately, it is antiferromagnetic. Nevertheless, one can imaging coupling it with ferromagnets, which are more easily measurable, to make a working device.
Another alternative lies in using the properties of topological defects like domain walls (DW), which have their own interesting properties. In particular, these objects can have a magnetic moment as well as interesting photo-electric properties. They can also be manipulated with an electrical field and as such, they offer potential for non-volatile storage, logic or optoelectronic devices.
One PhD project (Camille Blouzon) supported by the ANR “Multidolls” is to study bismuth ferrite DW properties, including photovoltaic and magnetic… A wide range of characterization technics as synchrotron radiation, neutron scattering, and original homemade experimental setups will be used.