Magneto-electric operators in neutron scattering

TL;DR

This paper derives an exact expression for neutron-electron magnetic interactions including magneto-electric operators, revealing new parity-odd contributions relevant in non-centrosymmetric materials.

Contribution

It introduces a comprehensive theoretical framework incorporating magneto-electric operators into neutron scattering analysis, expanding understanding of magnetic interactions in non-centrosymmetric systems.

Findings

Derived exact expression for magnetic neutron-electron interaction including magneto-electric operators

Identified key roles of spin anapole and toroidal operators in neutron scattering

Applied the theory to simulate neutron diffraction in copper oxide

Abstract

We succeed in deriving an exact expression for the magnetic interaction of neutrons and electrons including magneto-electric operators, allowed in the absence of a centre of inversion symmetry. Central characters are a spin anapole and an orbital (toroidal) analogue, in addition to familiar parity-even operators. A simulation of neutron diffraction by antiferromagnetic copper oxide makes full use of information inferred from a thorough investigation with resonant x-ray Bragg diffraction.