Absolute crystal and magnetic chiralities in the langasite compound Ba3NbFe3Si2O14 determined by polarized neutron and x-ray scattering

Abstract

We present a combined polarized neutron and x-ray scattering study on two enantiopure langasite single crystals aimed at the determination of their absolute structural and magnetic chiralities and the coupling between them. Our respective data sets unambiguously reveal two samples of opposite structural chirality, where the magnetic handedness is pinned by the structural one. Simple energy considerations of the magnetic exchange and single-ion anisotropy parameters reveal that it is not the Dzyaloshinskii-Moriya interaction but the local single-ion anisotropy on a triangular plaquette which plays a key role in stabilizing one of the two magnetic helices.

Neutron diffraction in MnSb2O6 : Magnetic and structural domains in a helicoidal polar magnet with coupled chiralities

“…For an enantiopure, the flipping ratios should be close to one set of predicted flipping ratios, which shows much more pronounced asymmetries as exemplified by the (511) and (153) reflections. The results are thus different from enantiopure Ba 3 NbFe 3 Si 2 O 14 single crystals which were previously studied [11,13,32].…”

“…In the reference frame of a moving neutron, the electric field of a noncentrosymmetric crystal creates an effective magnetic field which couples to the neutron spin. This neutron spin-orbit interaction results in a polarization-dependant scattering known as Schwinger scattering [30] which can be used as a probe of the structural handedness of the crystal [31,32].…”

“…In the local coordinates, where ẑ k i × k f is perpendicular to the scattering plane, the asymmetric Schwinger structure factor is given by [32]…”

Neutron diffraction in MnSb2O6: Magnetic and structural domains in a helicoidal polar magnet with coupled chiralities

“…This neutron spin-orbit interaction results in a polarizationdependant scattering known as Schwinger scattering 30 which can be used as a probe of the structural handedness of the crystal. 31,32 In the local coordinates, where ẑ k i ×k f is perpendicular to the scattering plane, the asymmetric Schwinger structure factor is given by: 32…”

Anomalous Hall effect in the coplanar antiferromagnetic coloring-triangular lattice

“…This kind of process could take place, for example, in the triangular antiferromagnet Ba 3 NbFe 3 Si 2 O 14 26 . It is important to mention that in a recent article the authors claim that the DMI is not strong enough to lift the chirality degeneracy 27 .…”