Scanning-tunneling microscopy (STM) combined with electron spin resonance (ESR) has enabled single-spin spectroscopy with nanoelectronvolt energy resolution and angstrom-scale spatial resolution, which allows quantum sensing and magnetic resonance imaging at the atomic scale. Extending this spectroscopic tool to a study of multiple spins, however, is nontrivial due to the extreme locality of the STM tunnel junction. Here we demonstrate double electron-electron spin resonance spectroscopy in an STM for two coupled atomic spins by simultaneously and independently driving them using two continuous-wave radio frequency voltages. We show the ability to drive and detect the resonance of a spin that is remote from the tunnel junction while read-out is achieved via the spin in the tunnel junction. Open quantum system simulations for two coupled spins reproduce all double-resonance spectra and further reveal a relaxation time of the remote spin that is longer by an order of magnitude than that of the local spin in the tunnel junction. Our technique can be applied to quantum-coherent multi-spin sensing, simulation, and manipulation in engineered spin structures on surfaces.
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http://dx.doi.org/10.1021/acsnano.3c04754 | DOI Listing |
Micromachines (Basel)
December 2024
State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, Xidian University, Xi'an 710071, China.
In this study, we aim to enhance the internal quantum efficiency (IQE) of AlGaN-based ultraviolet (UV) light-emitting diodes (LEDs) by using the short-period AlGaN/GaN superlattice as a tunnel junction (TJ) to construct polarized structures. We analyze in detail the effect of this polarized TJ on the carrier injection efficiency and investigate the increase in hole and electron density caused by the formation of 2D hole gas (2DHG) and 2D electron gas (2DEG) in the superlattice structure. In addition, a dielectric layer is introduced to evaluate the effect of stress changes on the tunneling probability and current spread in TJ.
View Article and Find Full Text PDFLangmuir
January 2025
Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, School of Chemistry and Chemical Engineering, Zhejiang Sci-Tech University, 928 Second Street, Zhejiang, Hangzhou 310018, China.
Molecule-electrode interfaces play a pivotal role in defining the electron transport properties of molecular electronic devices. While extensive research has concentrated on optimizing molecule-electrode coupling (MEC) involving electrode materials and molecular anchoring groups, the role of the molecular backbone structure in modulating MEC is equally vital. Additionally, it is known that the incorporation of heteroatoms into the molecular backbone notably influences factors such as energy levels and conductive characteristics.
View Article and Find Full Text PDFNanomaterials (Basel)
January 2025
Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland.
We compare the optical properties of four diode samples differing by built-in field direction and width of the InGaN quantum well in the active layer: two diodes with standard layer sequences and 2.6 and 15 nm well widths and two diodes with inverted layer ordering (due to the tunnel junction grown before the structure) also with 2.6 and 15 nm widths.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta, Canada T6G 2G2.
Rigid, conjugated molecules are excellent candidates as molecular wires since they can achieve full extension between electrodes while maintaining conjugation. Molecular design can be used to minimize the accessible pi surface and interactions between the bridging wire and the electrode. Polyynes are archetypal molecular wires that feature a rigid molecular framework with a cross-section of a single carbon atom.
View Article and Find Full Text PDFACS Nano
January 2025
College of Optical and Electronic Technology, China Jiliang University, 310018 Hangzhou, China.
Van der Waals (vdW) contact has been widely regarded as one of the most potential strategies for exploiting low-resistance metal-semiconductor junctions (MSJs) based on atomically thin transition-metal dichalcogenides (TMDs), but this method is still not efficient due to weak metal-TMD interfacial interactions. Therefore, an understanding of interfacial interactions between metals and TMDs is essential for achieving low-resistance contacts with weak Fermi level pinning (FLP). Herein, we report how the interfacial interactions between metals and TMDs affect the electrical contacts by considering more than 90 MSJs consisting of a semiconducting TMD channel and different types of metal electrodes, including bulk metals, MXenes, and metallic TMDs.
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