2D Materials Demonstrate Reversible Kondo Coupling Control via Atomic-Scale Vertical Manipulation
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The quest to control interactions between electron spins holds immense promise for future technologies, particularly in the field of spintronics. Benjamin Lowe, Bernard Field, and Dhaneesh Kumar, alongside colleagues including Daniel Moreno Cerrada, Oleksandr Stetsovych, and Julian Ceddia, have now demonstrated a remarkable level of control over these interactions at the atomic scale.
The team successfully manipulates the coupling between localized spins within a two-dimensional material and the electrons in a supporting substrate, achieving this through precise vertical positioning of the material itself. This mechanical control over ‘Kondo coupling’, a quantum mechanical interaction, represents a significant step towards designing and controlling spin-based devices with unprecedented precision, potentially paving the way for novel spintronic applications.
Kondo Effect Control Via Adsorption Height This research details the experimental and theoretical investigation of a two-dimensional metal-organic framework (MOF) deposited on a silver surface. Scientists focused on controlling the Kondo effect, a quantum phenomenon, within the MOF by manipulating its adsorption height using a scanning tunneling microscope. This control alters the strength of interaction, known as Kondo coupling, between localized spins within the MOF and the underlying metal substrate, effectively controlling the screening of these localized spins. Detailed parameter exploration within the Anderson impurity model assessed the sensitivity of the results to different model parameters, including on-site Coulomb repulsion, on-site energy, and the density of electronic states in the silver substrate. This analysis validates the conclusions and identifies potential sources of uncertainty, revealing that smaller values of on-site Coulomb repulsion and on-site energy may lead to larger differences in hybridization between the copper sites.
This research provides new insights into the Kondo effect and the role of substrate interactions in controlling the properties of localized spins. It demonstrates a new approach to designing materials with tailored electronic properties by controlling hybridization between localized spins and the substrate, with potential applications in quantum computing and other quantum technologies. Scanning tunneling microscopy showcases its power as a tool for manipulating materials at the atomic scale and controlling their electronic properties. Mechanical Control of Kondo Coupling in Kagome MOFs Scientists engineered a method to mechanically control Kondo coupling within a two-dimensional metal-organic framework (MOF) deposited on a silver substrate, achieving precise control over electron interactions at the atomic scale. The study pioneered a technique utilizing a scanning tunneling microscope probe to vertically manipulate the MOF, altering its adsorption height and, consequently, the strength of Kondo coupling between the MOF’s local spins and the substrate’s conduction electrons. Characterization via scanning tunneling microscopy and non-contact atomic force microscopy revealed distinct bright and dark copper sites within the MOF, differing in apparent height and confirming a structural origin for this variation. Precise measurements with atomic force microscopy quantified a 0. 2 Å adsorption height difference between these sites, demonstrating a lattice mismatch between the MOF and the silver substrate. Differential conductance measurements revealed a zero-bias Kondo peak, indicative of Kondo screening of localized electrons by the substrate conduction electrons, with the peak’s characteristics varying between the different copper sites. Scientists fitted the experimental data with a Fano function to extract key parameters, then determined the Kondo temperature for each copper site. This analysis revealed a Kondo temperature of 125 ±7 K for one set of copper sites and 162 ±16 K for another, demonstrating stronger Kondo screening for sites closer to the silver surface. Applying the Anderson single-impurity model, researchers established a relationship between Kondo temperature and electronic hybridization between the MOF orbitals and the silver states, providing a framework for understanding the observed differences in Kondo coupling and paving the way for atomic-scale control of spintronic technologies.
Kondo Effect Controlled in Kagome Material Scientists have achieved precise control over the Kondo effect in a two-dimensional material, demonstrating a new method for manipulating electron behavior at the atomic scale. The research focuses on a kagome metal-organic framework (MOF) grown on a silver surface, where localized electrons exhibit strong correlations and the potential for exotic quantum phases. Through vertical manipulation using a scanning tunneling microscope, the team demonstrated the ability to alter the strength of Kondo coupling, the interaction between localized electrons within the MOF and the conduction electrons of the substrate. Experiments revealed distinct differences in the adsorption height of copper atoms within the MOF, measured at 0. 2 Å using non-contact atomic force microscopy. These variations in height directly correlate with differing strengths of Kondo coupling, as evidenced by temperature-dependent scanning tunneling spectroscopy measurements. Analysis of the resulting data shows a Kondo temperature of 125 ±7 K for one type of copper site and 162 ±16 K for another, indicating stronger Kondo screening at the sites closer to the silver surface.
The team fitted experimental data to a theoretical model, extracting key parameters that describe the interaction between the MOF and the substrate. This analysis confirms that the observed differences in Kondo temperature are primarily driven by changes in electronic hybridization, specifically the strength of the coupling between the MOF orbitals and the silver states. The breakthrough delivers a new pathway for controlling electron correlations in two-dimensional materials, potentially enabling the design of advanced spintronic devices and the exploration of novel quantum phenomena. This precise control over Kondo coupling represents a significant step towards realizing atomic-scale control of electron behavior and harnessing the potential of strongly correlated materials. Kagome MOF Interactions Mechanically Controlled Researchers have demonstrated a method for controlling the strength of interactions between localized magnetic moments within a two-dimensional material. By manipulating the height of a kagome metal-organic framework (MOF) using an atomically sharp probe, the team successfully altered the strength of Kondo coupling, the interaction between the MOF’s local spins and the conduction electrons of the underlying substrate. This mechanical control of exchange coupling stems from variations in electronic hybridization between the MOF and the substrate, as confirmed by theoretical modelling. This achievement represents the first successful contact and manipulation of a two-dimensional MOF using a scanning tunneling microscope tip, opening possibilities for future transport measurements through these materials. The ability to tune magnetic interactions without relying on external magnetic fields could prove valuable in the development of spintronic technologies. 👉 More information 🗞 Atomic-scale control of substrate-spin coupling via vertical manipulation of a 2D metal-organic framework 🧠 ArXiv: https://arxiv.org/abs/2512.16194 Tags: