Kondo effect by controlled cleavage of a single-molecule contact

Abstract

Conductance measurements of a molecular wire, contacted between an epitaxial molecule-metal bond and the tip of a scanning tunnelling microscope, are reported. Controlled retraction of the tip gradually de-hybridizes the molecule from the metal substrate. This tunes the wire into the Kondo regime in which the renormalized molecular transport orbital serves as a spin impurity at half-filling and the Kondo resonance opens up an additional transport channel. Numerical renormalization group simulations suggest this type of behaviour to be generic for a common class of metal-molecule bonds. The results demonstrate a new approach to single-molecule experiments with atomic-scale contact control and prepare the way for the ab initio simulation of many-body transport through single-molecule junctions.

Atomic-Scale Control of Electron Transport through Single Molecules

“…While the importance of atomic structure and bonding for transport through single-molecule junctions has repeatedly been emphasized, investigations with atomic-scale control of the junction geometry are scarce. Recent scanning tunneling microscope (STM) experiments have provided structural information about the electrodes and the orientation of contacted molecules with atomic precision [12][13][14][15][16]. This opens an avenue for understanding and controlling the current flow through single molecules by combining transport measure ments with the atomic manipulation capabilities of a STM.…”

Research Update: Molecular electronics: The single-molecule switch and transistor

“…During the last few decades, several research groups have successfully managed to trap a single molecule between two electrical contacts. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] The most popular technique to contact a single molecule is the quantum mechanical break junction technique, where a nanoscopic junction is realized by controllably opening and closing a narrow metallic constriction. 8,9,[21][22][23] As an alternative, molecules are captured between a substrate and the apex of the tip of a scanning tunneling or atomic force microscope.…”

New directions in point-contact spectroscopy based on scanning tunneling microscopy techniques (Review Article)

“…This dynamics is nowadays exploited to build and manipulate atomic-size devices on surfaces. A few examples are the assembly of atomic-size structures on a surface [57,58,[64][65][66] or the manipulation of mesoscopic systems such as organic molecules [67][68][69][70][71][72][73]. The high stability and reproducibility of STM in manipulating adsorbates deposited on a surface is of fundamental importance to understand transport characteristics in view of future applications in functional nanoscale devices.…”

“…For this purpose STM operating at He temperature (4 K) are usually employed for atom manipulation in order to insure a high stability of the system during the process. Larger systems such as organic molecules are easier to manipulate by STM than single atoms [68][69][70]72,73]. Stability is also enhanced by the fact that systems as organic molecules often include a couple of ligands moieties which allow the molecules to bind covalently to the metal surface onto which they are deposited [68,72,73].…”

“…Stability is also enhanced by the fact that systems as organic molecules often include a couple of ligands moieties which allow the molecules to bind covalently to the metal surface onto which they are deposited [68,72,73]. STM manipulation has been performed on a very wide range of organic systems, from very small binary molecules [70] to more complex systems [68,69,72,73] which include large selfassembled molecular wires [67,71].…”