Space charge and screening of a supercritical impurity cluster in monolayer graphene
| Autor: | Kolomeisky, Eugene B., Straley, Joseph P. |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | Physical Review B 109, 075418 (2024) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.109.075418 |
| Popis: | Coulomb impurity of charge $Ze$ is known to destabilize the ground state of undoped graphene with respect to creation of screening space charge if $Z$ exceeds a critical value of $1/2\alpha$ set by material's fine structure constant $\alpha$. Recent experimental advances made it possible to explore this transition in a controlled manner by tuning $Z$ across the critical point. Combined with relatively large value of $\alpha$ this opens a possibility to study graphene's screening response to a supercritical impurity $Z\alpha\gg1$ when the screening charge is large, and the Thomas-Fermi analysis, that we revisit, is adequate. The character of screening in this regime is controlled by the dimensionless screening parameter $Z\alpha^{2}$. Specifically, for circular impurity cluster most of the screening charge in the weak-screening regime $Z\alpha^{2}\ll1$ is found to reside outside the cluster. The strong-screening regime $Z\alpha^{2}\gg1$ provides a realization of the Thomson atom: most of the screening charge is inside the cluster nearly perfectly neutralizing the source charge with the exception of a transition layer near cluster's edge where the rest of the space charge is localized. Comment: 8 pages, 1 figure, minor changes, version to be published in Phys. Rev. B |
| Databáze: | arXiv |
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