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arXiv · 1208.0775

Magneto-orbital helices and multiferroicity

N. J. Perks·R. D. Johnson·C. Martin·L. C. Chapon·P. G. Radaelli
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Abstract

Orbitally ordered states evolving coincidentally with structural distortions and magnetic ordering provide a novel route to controlling electronic and magnetic properties of materials through external fields. We report an unprecedented magneto-orbital helix in CaMn7O12, found to give rise to the largest magnetically induced ferroelectric polarisation measured to date. Characterisation of the structural modulation using x-ray diffraction, and analysis of magnetic exchange shows that orbital order is crucial in stabilising a chiral magnetic structure, thus allowing for electric polarisation. Additionally, the presence of a global structural rotation enables the coupling between this polarisation and magnetic helicity required for multiferrocitiy. These novel principles open up the possibility of discovering new high-temperature multiferroics.

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N. J. Perks, R. D. Johnson, C. Martin, L. C. Chapon, P. G. Radaelli. 2012-08-03. Magneto-orbital helices and multiferroicity. https://arxiv.org/abs/1208.0775

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