Formation mechanism of bound states in graphene point contacts

Abstract

Electronic localization in narrow graphene constrictions are theoretically studied, and it is found that long-lived (∼ 1 ns) quasi-bound states (QBSs) can exist in a class of ultra-short graphene quantum point contacts (QPCs). These QBSs are shown to originate from the dispersionless edge states that are characteristic of the electronic structure of generically terminated graphene in which pseudo time-reversal symmetry is broken. The QBSs can be regarded as interface states confined between two graphene samples and their properties can be modified by changing the sizes of the QPC and the interface geometry. In the presence of bearded sites, these QBS can be converted into bound states. Experimental consequences and potential applications are discussed.

Decomposition into propagating and evanescent modes of graphene ribbons

“…The origin of these resonances is attributed to the formation of quasi-bound states near the aperture due to the interference of edge states. 53 A typical behavior of lowestenergy resonance for N c ≪ N z is displayed in Fig. 4(c) Its width at the maximum is scaled with N z following a power law, Γ −1 ∼ N 3 z , in agreement with our analytical treatment.…”

“…4 (a)]. This type of aperture was studied by us 53 and it was analytically shown that peculiar low-energy resonant states could form due to the presence of edge states. In what follows, we revisit this phenomenon by a mode-matching approach.…”

Contact conductance of a graphene nanoribbon with its graphene nano-electrodes

“…18 Quantum point contacts for the GNR have been studied extensively by various groups. [19][20][21][22][23][24][25] Deng et al 25 predicted that long lived quasi-bound states originate from the dispersion-less edge states due to the electronic structure of generically terminated graphene. These quasibound states accounted for the interface states between two graphene sheets, and it was shown that their properties can be changed with the size and geometry of the interface contact.…”

Electron confinement induced by diluted hydrogen-like ad-atoms in graphene ribbons

“…The main feature of these states is that they are spread in a narrow energy window, so any electron from the leads injected at these energies easily passes across the system. 45,72 FIG. 10 The DFT calculations are performed within the superlattice approach using the density functional based tightbinding method implemented by the DFTB+ code 73 with the associated Slater-Koster parameters.…”