Chiral fluctuations in MnSi above the Curie temperature measured with polarized inelastic neutron scattering

TL;DR

This study uses polarized inelastic neutron scattering to reveal chiral, incommensurate paramagnetic fluctuations in MnSi above its Curie temperature, emphasizing the importance of antisymmetric interactions in its critical dynamics.

Contribution

It provides the first direct measurement of the antisymmetric part of the dynamical susceptibility in MnSi, highlighting the role of Dzyaloshinskii-Moriya interactions in its critical behavior.

Findings

Paramagnetic fluctuations are incommensurate and chiral.

Antisymmetric interactions are essential for accurate critical dynamics modeling.

Data aligns with SCR-theory including Dzyaloshinskii-Moriya interaction.

Abstract

Using polarized inelastic neutron scattering the antisymmetric part of the dynamical susceptibility in non-centrosymmetric MnSi is determined. The paramagnetic fluctuations are found to be incommensurate with the chemical lattice and to have a chiral character. We show that antisymmetric interactions must be taken into account to properly describe the critical dynamics in MnSi above the Curie temperature. The inelastic neutron data is interpreted within the framework of the SCR-theory, taking into account the Dzyaloshinskii-Moriya interaction.