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Controllable tunnel coupling and molecular states in a graphene double quantum dot
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10.1063/1.3676083
/content/aip/journal/apl/100/2/10.1063/1.3676083
http://aip.metastore.ingenta.com/content/aip/journal/apl/100/2/10.1063/1.3676083
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Figures

Image of FIG. 1.
FIG. 1.

(Color online) (a) Scanning electron microscope image of the structure of the designed multiple gated sample studied in this work. The double quantum dot have two isolated central islands of diameter 100 nm in series, connected by 20 × 20 nm tunneling barriers to source and drain contacts (S and D) and 30 × 20 nm tunneling barrier with each other. These gates are labeled by G1, GL, GM, GR, G2, in which gate GM, G1, and G2 are used to control the coupling barriers between the dots as well as the leads. Gates GL and GR are used to control and adjust the energy level of each dot. (b) Schematic of a representative device.

Image of FIG. 2.
FIG. 2.

(Color online) (a) Color scale plot of the differential conductance versus voltage applied on gate GL (VGL ) and gate GR (VGR ) at Vsd  = 20 μV, VG 1 = 0 μV, VGM  = 0 μV, and VG 2 = 0 μV. The honeycomb pattern we got stands for the typical charge stability diagram of coupled double quantum dots. (b) Pure capacitance model of a graphene double dot system. Zoom-in of a honeycomb structure (c) and a vertex pair (d) at Vsd  = 900 μV.

Image of FIG. 3.
FIG. 3.

(Color online) (a)-(c) Colorscale plot of the differential conductance versus voltage applied on gate GL (VGL ) and gate GR (VGR ) at Vbg  = 2.5 V for different VGL regimes. (d)-(f) Color scale plot of the differential conductance versus voltage applied on gate L (VGL ) and gate R (VGR ) for different back gate voltage Vbg . The trend of interdot tunnel coupling changing from weak to strong can be seen clearly. (g) Sketches of the characteristic electronic configurations with interdot tunnel coupling t.

Image of FIG. 4.
FIG. 4.

(Color online) (a) Colorscale plot of the differential conductance versus the energies of each dot EL and ER at Vsd  = 20 μV near the selected two vertices with dashed lines as guides to the eye. (b) Schematic of a single anticrossing and the evolution from the state localized in each dot to a molecule state extending across both dots.28 (c) E Δ dependence of the detuning . E Δ (circles) is measured from the separation of the two high conductance wings in (a). The line illustrates a fit of the data to Eq. (1).

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/content/aip/journal/apl/100/2/10.1063/1.3676083
2012-01-10
2014-04-18
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Controllable tunnel coupling and molecular states in a graphene double quantum dot
http://aip.metastore.ingenta.com/content/aip/journal/apl/100/2/10.1063/1.3676083
10.1063/1.3676083
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