Atomic-Scale Switching of Defects in Two-Dimensional Silver
/ Announcements
Scientists from the Paul Drude Institute, led by Van Dong Pham, in collaboration with a group from Penn State University (led by Joshua A. Robinson), have demonstrated unprecedented control over atomic-scale defects in a two-dimensional silver layer. The work was carried out within PDI’s Core Research Area (CReA) Nanoanalytics and has recently been published in Nano Letters.
The researchers studied a single layer of silver sandwiched between graphene and silicon carbide. Using low-temperature scanning tunneling microscopy, they identified two types of atomic-scale defects: missing silver atoms (vacancies) and vacancies replaced by impurities, likely silicon introduced during crystal growth. Each type of defect creates a localized electronic state that alters the electronic structure of the silver layer in its immediate vicinity.
Crucially, these defects can be actively switched between two metastable states using electrons injected from the microscope tip. This switching is reversible, leading to two well-defined ON and OFF conductance levels. The switching speed can be tuned by adjusting the tunneling current at a negative applied voltage, revealing that the process is driven by inelastic electron tunneling.
Graphene plays a key role in this system. Acting as a protective yet electronically transparent cover, it allows electrons to pass through while preserving the atomic structure underneath. This makes it possible to control individual defects with high precision, without damaging the material, and ensure possible operations of the system under ambient conditions.
Overall, this work opens a new route for harnessing atomic defects in two-dimensional metals as functional elements in future nanoelectronic and quantum devices operating at the ultimate, atomic-scale limit.
Title: Point defects and their dynamic behaviors in silver monolayer intercalated between graphene and SiC
Authors: V. D. Pham, A. Jain, C. Dong, L.-S. Lu, J. A. Robinson, A. Trampert, R. Engel-Herbert
Source: Nano Lett., tba, 5c05763 (2025)
DOI: 10.1021/acs.nanolett.5c05763
Core Research Area (CReA): Nanoanalytics