Vectorial Reconstruction of Magnetic Order Parameters using Electron Magnetic Linear Dichroism

Abstract

Determining the orientation of compensated magnetic order with nanometer resolution remains a major challenge because conventional magnetic probes primarily detect net magnetization. Here, we establish electron magnetic linear dichroism as a quantitative probe of the spin axis in transmission electron microscopy. Explicit inclusion of vectorial core-level exchange splitting into mixed-dynamic-form-factor simulations accounting for dynamical diffraction enables the calculation of the momentum- and energy-resolved dichroic response for an arbitrary Néel-vector or magnetization orientation. The magnetic linear contribution can be separated from nonmagnetic anisotropy and exhibits a characteristic angular dependence that enables reconstruction of the spin axis from a finite set of momentum-resolved electron-energy-loss spectra. Simulations for the antiferromagnetic and ferromagnetic phases of cubic FeRh show that this sensitivity persists from parallel illumination to atomically confined probes and over a broad range of crystal orientations and thicknesses. Electron magnetic linear dichroism therefore provides a route toward nanoscale vector imaging of compensated magnetic order in antiferromagnets and related magnetic materials.

Preprint-v2