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.