Deterministic Steering of Atoms in an Electron Microscope Achieved in the Layered Magnetic Semiconductor CrSBr

The ability to program physics at the atomic scale into materials is a dream for designing and exploring quantum phenomena on-demand. Although aberration-corrected scanning transmission electron microscopy (STEM) is a strong candidate for this task, achieving deterministic modifications remains challenging. This is due to the need for even higher precision in electron beam control than is currently available, requiring extreme management of distributing electrons in both space and time. Widely studied atomically thin materials, such as hBN, MoS₂ or graphene, are furthermore challenging to manipulate owing to their all-surface nature.<br/>In this talk we will demonstrate the deliberate and repeated atomically precise manipulation of individual Cr atoms in the bulk layered magnetic semiconductor CrSBr [1, 2]. Irradiating an area of multilayer CrSBr with electrons drives a structural phase transformation with Cr atoms becoming mobile and moving into interstitial sites in the van der Waals gap [3]. Leveraging this surprising displacement mechanism, we utilize several beam control strategies we have developed, that can deliver electrons with a positioning precision of sub-20 picometer [4, 5], to control individual Cr atom movement in space and time in multilayer crystals [6]. We show that the precision of our real-time electron beam control enables a quantitative study of displacement kinetics. Using these capabilities, we demonstrate deterministic, repeatable, atom number-conserving and deliberate multi-directional atom steering in a thick specimen (&gt; 10 nm). The approaches and results represent a blueprint towards creating identical optically active spin defects in the solid-state in 2D and bulk materials. This is of strong interest for engineering artificial atomic many-body quantum systems, intentionally controlling physics at the atomic level in materials over microscopic and even macroscopic length scales.<br/><br/><b>References.</b><br/>[1] J. Klein et al., <i>ACS Nano <b>17</b>, 5316–5328</i> (2023)<br/>[2] J. Klein et al., <i>ACS Nano</i> <b><i>17</i></b><i>, 288–299</i> (2023)<br/>[3] J. Klein et al., <i>Nat. </i><i>Comms. <b>13</b>, 5420</i> (2022)<br/>[4] K. M. Roccapriore, F. M. Ross and J. Klein <i>manuscript</i> <i>under review</i><br/>[5] J. Klein, K. M. Roccapriore, F. M. Ross, <i>U. S. Provisional Pat.</i> Ser. No. 63/601,529, Filed November 21, 2023.<br/>[6] J. Klein, K. M. Roccapriore et al., <i>manuscript</i> <i>in preparation</i><br/>[7] 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.