Attraction-repulsion transition in the interaction of adatoms and vacancies in graphene

Abstract

The interaction of two resonant impurities in graphene has been predicted to have a long-range character with weaker repulsion when the two adatoms reside on the same sublattice and stronger attraction when they are on different sublattices. We reveal that this attraction results from a single energy level. This opens up a possibility of controlling the sign of the impurity interaction via the adjustment of the chemical potential. For many randomly distributed impurities (adatoms or vacancies) this may offer a way to achieve a controlled transition from aggregation to dispersion.

Modulation of Kekulé adatom ordering due to strain in graphene

“…Calculations were performed using version 0.6 of the Julia language [39]. In the weakcoupling limit the results agree with analytical expressions for U that were obtained in the literature for unstrained graphene [31]. It was shown, using a simplified adatom model, that in the limit of weakly coupled adatoms, U exhibit a Kekulé modulation given by…”

“…Consider for simplicity only two adatoms in the system k = 1,2 on sublattices σ 1 and σ 2 at a distance r = r 2 − r 1 . The interaction potential U σ 1 σ 2 (r) can be written [29,31,38] as the total energy of all the electrons in the system, as they adjust to the presence of the adatoms,…”

“…Alternative derivations with different (but formally equivalent) forms of these equations can be found, e.g., in Refs. [29,31,38].…”

“…6. It may be shown analytically [31] that a pristine and fully coherent graphene substrate leads to a same-sublattice adatom potential U AA (r) = v AA (r) cos(2πν r ) that scales asymptotically as v AA (r) ∼ 1/r 3 with interadatom distance (at shorter distances, deviations are predicted depending on the adatom coupling strength [29]). This asymptotic result, however, assumes that dissipation is completely absent in the graphene electron liquid.…”

Long-range exchange interaction between magnetic impurities in graphene

“…The potential part W (R) has been studied both for weak 21 and strong 21,22 impurity strength U . To the con-…”