Atomic-Scale Processing of the One-Dimensional van der Waals Materials

The thermodynamic stability of strictly two-dimensional (2D) and one-dimensional (1D) crystals is the subject of a long-standing debate. It follows from the harmonic approximation that the thermal fluctuations destroy the long-range order, resulting in the melting of a 2D and 1D lattice at a finite temperature. However, experiments with graphene have demonstrated that 2D van der Waals materials can be stable and efficiently manipulated at the level of individual atomic planes. In this presentation, we describe the exfoliation and processing of two 1D van der Waals materials at the atomic scale [1]. We show that 1D van der Waals materials with low exfoliation energy, such as Ta₂Se₈I, can be processed with electron beams to achieve suspended individual atomic chains. Another material, MoI₃, can be chemically exfoliated to the limit of individual atomic chains. Ab initio calculations confirm the thermodynamic stability of individual atomic chains in these 1D van der Waals materials. These results demonstrate that the top-down approach in material processing can be extended to the atomic-scale limit. [1] J. Teeter, et al., “Achieving the 1D atomic chain limit in Van der Waals crystals,” Advanced Materials, 2409898 (2024). A.A.B. acknowledges VBFF support via N00014-21-1-2947. DFT calculations were performed on STAMPEDE3 at TACC and EXPANSE at SDSC under allocation DMR130081 from the AC-CESS program, which is supported by NSF grants #2138259, #2138286, #2138307, #2137603, and #2138296.