Visualizing designer quantum states in stable macrocycle quantum corrals

Peng, Xinnan; Mahalingam, Harshitra; Dong, Shaoqiang; Mutombo, Pingo; Su, Jie; Telychko, Mykola; Song, Shaotang; Lyu, Pin; Ng, Pei Wen; Wu, Jishan; Jelı́nek, Pavel; Родин, Александр; Lu, Jiong

doi:10.1038/s41467-021-26198-8

Cited by 14 publications

(19 citation statements)

References 62 publications

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“…The extracted Lewis structure of the ribbon (referred to as 2B-575*-aGNR) is shown in Figure b. Pentagonal rings are known to appear when methyl groups of the precursor detach during the polymerization reaction. ,, This type of defect at the linking position is the most common structure we find in an analysis of 16 ribbons (see also SI Figure 4).…”

Section: Resultsmentioning

confidence: 89%

Addressing Electron Spins Embedded in Metallic Graphene Nanoribbons

et al. 2022

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Spin-hosting graphene nanostructures are promising metal-free systems for elementary quantum spintronic devices. Conventionally, spins are protected from quenching by electronic band gaps, which also hinder electronic access to their quantum state. Here, we present a narrow graphene nanoribbon substitutionally doped with boron heteroatoms that combines a metallic character with the presence of localized spin 1/2 states in its interior. The ribbon was fabricated by onsurface synthesis on a Au(111) substrate. Transport measurements through ribbons suspended between the tip and the sample of a scanning tunneling microscope revealed their ballistic behavior, characteristic of metallic nanowires. Conductance spectra show fingerprints of localized spin states in the form of Kondo resonances and inelastic tunneling excitations. Density functional theory rationalizes the metallic character of the graphene nanoribbon due to the partial depopulation of the valence band induced by the boron atoms. The transferred charge builds localized magnetic moments around the boron atoms. The orthogonal symmetry of the spin-hosting state's and the valence band's wave functions protects them from mixing, maintaining the spin states localized. The combination of ballistic transport and spin localization into a single graphene nanoribbon offers the perspective of electronically addressing and controlling carbon spins in real device architectures.

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Section: Resultsmentioning

confidence: 89%

Addressing Electron Spins Embedded in Metallic Graphene Nanoribbons

et al. 2022

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“…Scanning tunneling spectroscopy shows the confinement of the surface electrons into the pores of the molecular networks, leading to levels shifted upward by 0.1–0.3 eV above the Fermi level. As a result of the strong coupling between these artificial atoms, the confined levels form bonding/antibonding states, leading to the formation of an occupied and an unoccupied band delocalized over the lattice. , Force (dissipation) versus voltage spectroscopy acquired above the lattices systematically shows steps (peaks) at both voltage polarities similar to charging/discharging events in 0D quantum dots by local tip gating. We interpret this phenomenon as a change of the band occupancy induced by electrostatic gating from the AFM tip, which is rationalized using a capacitance model that includes the capacitance of the substrate and tip as well as the quantum capacitance of the confined states.…”

Section: Discussionmentioning

confidence: 95%

Energy Dissipation from Confined States in Nanoporous Molecular Networks

et al. 2022

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Crystalline nanoporous molecular networks are assembled on the Ag(111) surface, where the pores confine electrons originating from the surface state of the metal. Depending on the pore sizes and their coupling, an antibonding level is shifted upward by 0.1−0.3 eV as measured by scanning tunneling microscopy. On molecular sites, a downshifted bonding state is observed, which is occupied under equilibrium conditions. Low-temperature force spectroscopy reveals energy dissipation peaks and jumps of frequency shifts at bias voltages, which are related to the confined states. The dissipation maps show delocalization on the supramolecular assembly and a weak distance dependence of the dissipation peaks. These observations indicate that two-dimensional arrays of coupled quantum dots are formed, which are quantitatively characterized by their quantum capacitances and resonant tunneling rates. Our work provides a method for studying the capacitive and dissipative response of quantum materials with nanomechanical oscillators.

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“…Here we discuss two-dimensional artificial atoms created by quantum corals formed by CO on Cu(111). We mention here that such corrals can also be formed by ring-shaped molecular architectures …”

Section: Artificial Atoms and Molecules In Two Dimensionsmentioning

confidence: 99%

“…This methodology can thus provide a one-on-one relationship between electronic band structure and the lattice geometry, a powerful tool to test concepts and theories. We remark here that artificial atoms, molecules, and lattices can also be engineered by assembling corral-type organic structures and periodic organic scaffolds to mold the two-dimensional electron gas present on the surface of noble metals. − …”

Section: Analogue Quantum Simulations With Electronic Artificial Latt...mentioning

confidence: 99%

Electronic Quantum Materials Simulated with Artificial Model Lattices

et al. 2022

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The band structure and electronic properties of a material are defined by the sort of elements, the atomic registry in the crystal, the dimensions, the presence of spin−orbit coupling, and the electronic interactions. In natural crystals, the interplay of these factors is difficult to unravel, since it is usually not possible to vary one of these factors in an independent way, keeping the others constant. In other words, a complete understanding of complex electronic materials remains challenging to date. The geometry of two-and one-dimensional crystals can be mimicked in artificial lattices. Moreover, geometries that do not exist in nature can be created for the sake of further insight. Such engineered artificial lattices can be better controlled and fine-tuned than natural crystals. This makes it easier to vary the lattice geometry, dimensions, spin−orbit coupling, and interactions independently from each other. Thus, engineering and characterization of artificial lattices can provide unique insights. In this Review, we focus on artificial lattices that are built atom-by-atom on atomically flat metals, using atomic manipulation in a scanning tunneling microscope. Cryogenic scanning tunneling microscopy allows for consecutive creation, microscopic characterization, and band-structure analysis by tunneling spectroscopy, amounting in the analogue quantum simulation of a given lattice type. We first review the physical elements of this method. We then discuss the creation and characterization of artificial atoms and molecules. For the lattices, we review works on honeycomb and Lieb lattices and lattices that result in crystalline topological insulators, such as the Kekuléand "breathing" kagome lattice. Geometric but nonperiodic structures such as electronic quasi-crystals and fractals are discussed as well. Finally, we consider the option to transfer the knowledge gained back to real materials, engineered by geometric patterning of semiconductor quantum wells.

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Visualizing designer quantum states in stable macrocycle quantum corrals

Cited by 14 publications

References 62 publications

Addressing Electron Spins Embedded in Metallic Graphene Nanoribbons

Addressing Electron Spins Embedded in Metallic Graphene Nanoribbons

Energy Dissipation from Confined States in Nanoporous Molecular Networks

Electronic Quantum Materials Simulated with Artificial Model Lattices

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