Control of Electron Beam-Induced Phase Transformations in a 2D Magnet through Crystal Orientation

Controlling and studying materials properties at the atomic scale is essential for understanding fundamental physics and developing novel devices that utilize size and structure-dependent electronic and optical phenomena. The family of layered 2D magnets¹ provides opportunities to extend towards magnetic property control. For 2D magnets, especially the highly anisotropic materials AgCrP₂S₆ and CrSBr, we find that the focused electron beam in the scanning transmission electron microscope is a powerful tool for sculpting the atomic structure, with the potential to modulate the local magnetic properties.^2,3

In this work, we probe the degree of structural control through selection of the area and direction of electron beam irradiation. In CrSBr, irradiation of a broad area with high energy electrons displaces Cr atoms into the vdW gap to create a configuration in which the layer direction is rotated.³ By irradiating from different crystallographic directions we find, unexpectedly, the nature of the transformed structure itself depend strongly on the orientation between the beam and the crystal. We analyze image series recorded during the transformation to quantify reaction kinetics, and we successively irradiate small areas to determine nucleation pathways, aiming to provide insights into beam-solid interactions by comparing the orientation dependence of these measurements.

1 Gibertini, M. et al. Nat. Nanotechnol. 14 (2019)

2 Park, E. et al. Adv. Mat. 36 (2024)

3 Klein, J. et al. Nat. Commun. 13 (2022)