V. Caignaert, A. Maignan, K. Singh, Ch. Simon, V. Pralong, B. Raveau, J. F. Mitchell, H. Zheng, L. Chapon
The single crystal study of CaBaCo4O7, a non collinear ferrimagnet (TC=64K), with a polar orthorhombic space group (Pbn21) between 4 K and 293 K, shows the appearance below TC of a large electric polarization along its c axis, reaching 17mC.m-2 at 10K. Moreover, the present magnetoelectric measurements, are fully consistent with the m'm2' magnetic point group, strongly supporting that this oxide is ferrotoroidic. Importantly, CaBaCo4O7 exhibits a large magnetoelectric coupling of magnitude 6.7ns/m at 65K and for H=2T. This oxide, which belongs to the '114' structural family, and where the magnetic ions exhibit the tetrahedral coordination, not yet reported to date for improper ferroelectrics, opens an avenue for the search of new multiferroics.
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http://arxiv.org/abs/1302.5541
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