Conductive Atomic Force Microscopy for Defect Exploration of the 2D Magnetic Semiconductor CrSBr

Defects in two-dimensional (2D) layered materials underpin important materials properties, affect behavior, and drive performance for a wide range of desirable applications. Chromium sulfide bromide, CrSBr, an air-stable magnetic semiconductor, is a van der Waals (vdW) layered material with exceptional potential for use in spintronics and quantum technologies [1, 2]. While its optical, electronic and magnetic properties have been widely studied, there is limited information on the types and densities of defects, as well as how they influence the properties of CrSBr [3, 4, 5].<br/><br/>Here, we investigate defects in CrSBr grown by chemical vapor transport (CVT) using conductive atomic force microscopy (cAFM). This microscopy technique has recently been demonstrated to be highly effective in assessing defects over large areas in layered materials [6]. Employing cAFM yielded results previously only trusted to be achievable with more tedious, complex, and costly microscopy methods, such as scanning tunneling microscopy (STM) or transmission electron microscopy (TEM). In this talk, we reinforce the advantages and accuracy of cAFM for a statistics-driven approach to defect characterization. We extend our studies to compare cAFM measurements made on CrSBr formed in different growth environments (Br-rich, S-rich), after annealing at high temperature, and grown with the addition of transition-metal dopants (V, Mn, Mo, and Fe). We offer analysis of how crystal growth, post-processing, or doping influences the defect properties (densities, size, origin) in each sample. Our results are supported by experimental STM data and theoretical calculations. Finally, we provide discussion of the expected effects of the defects on sample properties and subsequent potential for applications and functionalities.<br/><br/><b>References.</b><br/>[1] Wilson, N. et al. Nature Mater. 20, 1657-1662 (2021)<br/>[2] Telford, E. J. et al. Adv. Mater. 32, 2003240 (2020)<br/>[3] Klein, J. et al. ACS Nano 17, 288-299 (2023)<br/>[4] Klein, J. et al. Nature Comm. 13, 5420 (2022)<br/>[5] Torres, K. et al. Adv. Funct. Mater. 33, 2211366 (2023)<br/>[6] Xu, K. et al. ACS Nano 17, 24743-24752 (2023)