Abstract
In this paper, we describe the formation of local resonances in graphene in the presence of magnetic adatoms containing localized orbitals of arbitrary symmetry, corresponding to any given angular momentum state. We show that quantum interference effects which are naturally inbuilt in the honeycomb lattice in combination with the specific orbital symmetry of the localized state lead to the formation of fingerprints in differential conductance curves. In the presence of Jahn–Teller distortion effects, which lift the orbital degeneracy of the adatoms, the orbital symmetries can lead to distinctive signatures in the local density of states. We show that those effects allow scanning tunneling probes to characterize adatoms and defects in graphene.
Highlights
Graphene is a single atomic layer of graphite whose low energy quasi-particles behave as massless Dirac fermions [1,2,3]
The microscopic theory of STM is well understood in metallic hosts [19, 20], in graphene the sublattice quantum numbers play a role in the interference effects that drive the emergence of Fano resonances [21] nearby adatoms, in the presence of an STM tip
The outline of the paper is as follows: in section 2, we describe the generic zerodimensional Hamiltonian of an adatom in graphene; in section 3 we briefly describe the role of the orbital symmetry into the formation of local magnetic moments and we show the manifestation of those orbital symmetries in the local density of states (LDOS), whenever the adatom hybridizes with two or more carbon atoms
Summary
Graphene is a single atomic layer of graphite whose low energy quasi-particles behave as massless Dirac fermions [1,2,3]. In the presence of local Jahn–Teller distortions that lift orbital degeneracies, we show that the adatoms can induce distinctive signatures of the individual orbital symmetries directly in the LDOS of graphene, which can be measured with local energy resolved spectroscopy experiments. This effect is not present in ordinary host metals.
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