Femtoscale
atomic displacements in crystals play a big role in the electronic
properties
of exotic multiferroics materials, generating a mutual interaction
between
magnetic and ferroelectric macroscopic properties, of potential interest
in the
domain of advanced magnetic material for electronics. These materials
combine
both the crystallographic and magnetic symmetries to produce oriented
displacements of atomic positions, as pictorially represented in the art
image,
leading to a control of electric polarization by a magnetic field and
viceversa. (credit: Ghiandoni/Paolasini)
UCL scientists are part of an international team which has developed a novel X-ray technique for imaging atomic displacements in materials with unprecedented accuracy. The team has applied the technique to determine how a recently discovered class of exotic materials - multiferroics - can be simultaneously both magnetically and electrically ordered. Multiferroics are candidate materials for new classes of electronic devices. The discovery, a major breakthrough in understanding multiferroics, is published in Science (2 September 2011) and the authors include scientists from the European Synchrotron Radiation Facility (ESRF) in Grenoble (France), the University of Oxford and the London Centre for Nanotechnology at UCL. Magnets are polarised with a north and a south pole, a characteristic which is understood to arise from the alignment of magnet moments carried by atoms in magnetic materials. Certain other materials, known as ferroelectrics, exhibit a similar effect for electrical polarisation. The exotic 'multiferroic' materials combine both an ordered arrangement of atomic magnetic moments and ferroelectric polarisation, with a strong coupling between these two usually separate phenomena.
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