Magnetic characterization of the non centrosymmetric Ba3NbFe3Si2O14 langasite

The potential relevance of the Ba₃NbFe₃Si₂O₁₄ langasite in the field of multiferroism was investigated. Interesting properties were expected, in particular in view of the frustrating stacking of its magnetic Fe³⁺ cations into triangular planes of triangle units. We hereafter report results of specific heat and magnetic measurements, Mössbauer spectroscopy and neutron diffraction. A peculiar magnetic structure is found out at low temperature. The Fe³⁺ magnetic moments adopt a triangular 120° configuration within each triangle, which is in-phase propagated in each triangular plane and is helically modulated from plane to plane.