Angstrom-Scale Imaging of Magnetization in Antiferromagnetic Fe$_2$As via 4D-STEM

TL;DR

This paper introduces a novel 4D-STEM imaging approach combined with computational tools to visualize and analyze magnetization at the angstrom scale in antiferromagnetic Fe$_2$As, enabling detailed magnetic characterization.

Contribution

The study develops new imaging modes using magnetic diffraction peaks and introduces Magnstem, a quantum scattering simulation code, to enhance magnetic imaging at atomic resolution.

Findings

Achieved 6 Å spatial resolution in magnetic imaging.

Identified optimal conditions for separating magnetic signals.

Demonstrated visualization of the magnetic lattice in Fe$_2$As.

Abstract

We demonstrate a combination of computational tools and experimental 4D-STEM methods to image the local magnetic moment in antiferromagnetic Fe$_2$As with 6 angstrom spatial resolution. Our techniques utilize magnetic diffraction peaks, common in antiferromagnetic materials, to create imaging modes that directly visualize the magnetic lattice. Using this approach, we show that center-of-mass analysis can determine the local magnetization component in the plane perpendicular to the path of the electron beam. Moreover, we develop Magnstem, a quantum mechanical electron scattering simulation code, to model electron scattering of an angstrom-scale probe from magnetic materials. Using these tools, we identify optimal experimental conditions for separating weak magnetic signals from the much stronger interactions of an angstrom-scale probe with electrostatic potentials. Our techniques should be useful for characterizing the local magnetic order in systems such in thin films, interfaces, and domain boundaries of antiferromagnetic materials, which are difficult to probe with existing methods.