Interplay of boundary states of graphene nanoribbons with a Kondo impurity

Abstract

We investigate the interplay of two highly localized, nearly degenerate electronic states, namely, a zero-energy edge mode in a graphene nanoribbon on the one hand and an Abrikosov-Suhl resonance located at a Kondo impurity on the other. On-surface synthesis of the ribbon structures in combination with intercalation of singleatom Kondo impurities by atomic manipulation in a scanning tunneling microscope junction offer full control of the atomic geometry of the system. Density functional theory provides the microscopic description to scrutinize the electronic features observed in experiment. We find the interaction of the two localized states and the resulting signatures of Kondo physics to be very sensitive to the placing of the atom, suggesting its use as a laboratory to study the interplay of the Kondo effect with other zero-bias anomalies as well as to tailor these states by controlling the atomic-scale coupling.

On‐Surface Synthesis of Chiral Graphene Nanoribbon Segments via the Quarter‐Anthryl on Au(111) Surface

“…Elaboration in detail is that the spectrum taken at the bottom position depicts an obvious resonance at the Fermi level while the upper one shows two resonances at the Fermi level and at about 30 mV, which corresponds to the previous reported end‐state. [ 20 ] The presence of the resonance at the Fermi level reminds us to take the charge transfer into consideration. We performed the deformation charge density of the optimized 1U on the Au(111) (Figure S5a,b, Supporting Information), and the result shows the existence of charge transfer behavior between the 1U and the underneath substrate (more than 1 e − from the 1U to substrate).…”

“…[16] The fabricated quarteranthene with the blocking groups are revealed to manifest the antiferromagnetic (AFM) ground state, which is verified by the superconducting quantum interference device. With the existence of both reactive zigzag carbon edges, the quarteranthene possesses essential structural elements to induce the singly occupied edge states [17][18][19][20] and to bring topological phase transition behavior in the chiral graphene nanoribbons (chGNRs). [14] Lateral fusion or extension strategy has been reported in pristine [21,22] and doped GNRs [23] to enrich the topologies of GNRs and to modulate the electronic properties of GNRs.…”

Length‐Dependent Magnetic Evolution of Anthenes on Au(111)

“…Notably, the narrow‐bias‐range spectral measurements of (4,7)‐NG indicated molecular motion (Figure S5), which hinders temperature‐dependent experiments at high temperatures. Furthermore, 7‐AGNR, considered an upsized (n,7)‐NG, experiences slight upshifts of the end states because of hole doping on Au(111), as indicated in Figure 3a [36–38] . Calculated charge density difference shows a modest charge transfer of 1.2 e − and 0.85 e − from optimized (4,7)‐ and (3,7)‐NG to substrate (Figure S8).…”

Quantum Phase Transition in Magnetic Nanographenes on a Lead Superconductor

“…Up to date, the magnetism of most impurities originates from highly localized d/f orbitals of transitional metals, where crystal field and spin–orbit coupling cause a noticeable magnetic anisotropy on surfaces, ,,, hindering the study of intrinsic quantum spins interacting with Cooper pairs. Recently, a new type of delocalized π electron magnetism has been realized in small pieces of nanographenes − , − and chiral nanographene nanoribbons ,, by using advances of surface chemistry, , allowing for precise engineering of their magnetic properties down to the single-chemical-bond level. , The magnetism of nanographene is distinct from transitional metals in three aspects: (i) the spin density is delocalized inside the molecule, , (ii) the spin–orbit coupling of the graphene material is negligible, and (iii) the magnetic ground state can be easily engineered by introducing sublattice imbalance according to Lieb’s theorem. , Additionally, such a large-size nanographene hosts negligible magnetic anisotropy on surfaces due to its reduced crystal field splitting and thus can be viewed as ideal quantum spins on surfaces. , …”