Scalable Atomic Fabrication in Electron Microscopy—Precise Control of Cr Atoms in CrSBr

The ability to program physics at the atomic scale into materials is a long-standing goal for designing and exploring quantum phenomena. Although aberration-corrected scanning transmission electron microscopy (STEM) is a strong candidate for this task, achieving deterministic, repeatable modifications of materials over large areas remains challenging owing to the demanding need for precise electron beam control and effective management of electron distribution in space and time. Atomically thin materials, such as graphene, hBN, and MoS₂, which have been widely studied, pose additional difficulties because of their all-surface nature.

In this talk, we demonstrate fully scalable, atomically precise manipulation using electron microscopy, achieving deterministic manipulation of Cr atoms at thousands of selected locations in the bulk layered magnetic semiconductor CrSBr [1, 2]. Exposing multilayer CrSBr to electrons induces a structural phase transformation, in which Cr atoms become mobile and move to interstitial sites in the van der Waals gap. [3] Motivated by this displacement mechanism, we developed several beam control strategies to (i) consistently position the electron beam with sub-20 pm precision [4, 5] and (ii) perform specific beam motions to control the movement of Cr atoms in space and time [5]. With precise positioning and directed scanning, we show atom-number conserving steering of Cr atoms in user-selected crystallographic directions. Moreover, controlled local scanning allows real-time monitoring of Cr atom movements between the initial and interstitial states, revealing atom dynamics with a time resolution of a few milliseconds. Combining these approaches, we automate the microscope to realize the deterministic and repeatable construction of ordered Cr interstitial superlattice structures of high density as well as nonperiodic structures that span fields of view over tens of nanometers and are generated in minutes. Our results demonstrate the potential of electron microscopy for intentionally controlling physics through defect engineering, not only at the atomic level but also on macroscopic length scales.

[1] J. Klein et al., ACS Nano 17, 5316–5328 (2023)
[2] J. Klein et al., ACS Nano 17, 288–299 (2023)
[3] J. Klein et al., Nat. Comms. 13, 5420 (2022)
[4] K.M. Roccapriore, F. M. Ross and J. Klein under review
[5] J. Klein, K. M. Roccapriore et al., in preparation
[6] STEM beam control work was supported by Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.