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  Hamann-Borrero, J.E.; Partzsch, S.; Valencia, S.; Mazzoli, C.; Herrero-Martin, J.; Feyerherm, R.; Dudzik, E.; Hess, C.; Vasiliev, A.; Bezmaternykh, L.; Büchner, B.; Geck, J.: Magnetic frustration, phase competition, and the magneto-electric effect in NdFe₃(BO₃)₄. Physical Review Letters 109 (2012), p. 267202/1-5

10.1103/PhysRevLett.109.267202
Open Access Version (externer Anbieter)

Abstract:
We present an element selective resonant magnetic x-ray scattering study of NdFe3(BO3)4 as a function of temperature and applied magnetic field. Our measurements show that the magnetic order of the Nd sublattice is induced by the Fe spin order. When a magnetic field is applied parallel to the hexagonal basal plane, the helicoidal spin order is suppressed and a collinear ordering, where the moments are forced to align in a direction perpendicular to the applied magnetic field, is stabilized. This result excludes a noncollinear spin order as the origin of the magnetically induced electric polarization in this compound. Instead our data imply that magnetic frustration results in a phase competition, which is the origin of the magnetoelectric response.