Tunneling in Graphene/h-BN/Graphene Heterostructures through Zero-Dimensional Levels of Defects in h-BN and Their Use as Probes to Measure the Density of States of Graphene

Khanin, Yu. N.; Вдовин, Е. Е.; Grigor’ev, M. V.; Makarovsky, O.; Alhazmi, Manal; Морозов, С. В.; Mishchenko, Artem; Новоселов, К. С.

doi:10.1134/s0021364019070051

Cited by 8 publications

(6 citation statements)

References 26 publications

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“…1 a). This results in single charging behavior characteristic of quantum dots, as seen both in hBN and TMDs 10 , 33 – 35 . The dimension of a dot embedded within barriers depends on the type of defect and dielectric properties of the medium, and can range from the atomic size to a few nm 34 , 36 .…”

Section: Resultsmentioning

confidence: 98%

Quantum-dot assisted spectroscopy of degeneracy-lifted Landau levels in graphene

et al. 2020

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Energy spectroscopy of strongly interacting phases requires probes which minimize screening while retaining spectral resolution and local sensitivity. Here, we demonstrate that such probes can be realized using atomic sized quantum dots bound to defects in hexagonal Boron Nitride tunnel barriers, placed at nanometric distance from graphene. With dot energies capacitively tuned by a planar graphite electrode, dot-assisted tunneling becomes highly sensitive to the graphene excitation spectrum. The spectra track the onset of degeneracy lifting with magnetic field at the ground state, and at unoccupied excited states, revealing symmetry-broken gaps which develop steeply with magnetic field - corresponding to Landé g factors as high as 160. Measured up to B = 33 T, spectra exhibit a primary energy split between spin-polarized excited states, and a secondary spin-dependent valley-split. Our results show that defect dots probe the spectra while minimizing local screening, and are thus exceptionally sensitive to interacting states.

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Section: Resultsmentioning

confidence: 98%

Quantum-dot assisted spectroscopy of degeneracy-lifted Landau levels in graphene

et al. 2020

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“…Similarly, when V g = 1.65 V (blue curve) a peak in the magnitude of the current emerges close to V b = 0. These peaks occur when there is an alignment in energy of the localised state, E 1 , with LLs in the two graphene layers 21 . In effect, the localised state in the hBN barrier acts as a "stepping stone" for electrons tunnelling between the Landau levels of the two graphene electrodes, see inset of Fig.…”

Section: Resultsmentioning

confidence: 99%

“…When the lattices of the graphene layers are aligned so that their relative angular misorientation (twist angle) is small, ≲3°, electrons can tunnel coherently between the Dirac cones of the two layers with the conservation of momentum [8][9][10][11][12][13][14][15] . When the twist angle is large, an electron must scatter in order to tunnel between the misaligned Dirac cones; in this case, tunnelling can occur by phonon-assisted electron tunnelling [16][17][18] or by hopping via defects or impurities within the tunnel barrier [18][19][20][21][22][23][24][25][26] . The large twist angle of ≈30°between the two graphene layers in our devices ensures that direct band-to-band tunnelling with conservation of in-plane momentum is suppressed.…”

mentioning

confidence: 99%

“…A high quality hBN tunnel barrier typically contains within its band gap only a small number of strongly localised defect states, each with a sharply-defined energy level. Such a quantised state can provide a channel through which electrons can tunnel resonantly from one graphene layer to the other [18][19][20][21][22][23][24][25][26] . We have selected a device with a single active localised state within the tunnel barrier.…”

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confidence: 99%

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A magnetically-induced Coulomb gap in graphene due to electron-electron interactions

et al. 2023

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Insights into the fundamental properties of graphene’s Dirac-Weyl fermions have emerged from studies of electron tunnelling transistors in which an atomically thin layer of hexagonal boron nitride (hBN) is sandwiched between two layers of high purity graphene. Here, we show that when a single defect is present within the hBN tunnel barrier, it can inject electrons into the graphene layers and its sharply defined energy level acts as a high resolution spectroscopic probe of electron-electron interactions in graphene. We report a magnetic field dependent suppression of the tunnel current flowing through a single defect below temperatures of ~2 K. This is attributed to the formation of a magnetically-induced Coulomb gap in the spectral density of electrons tunnelling into graphene due to electron-electron interactions.

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“…Coupling defect-dots to source and drain electrodes entails placing an insulating layer between two conductors − the same geometry used for tunnel junctions stacked using the vdW transfer technique 31,32 (Figure 1(a)). This results in single charging behavior characteristic of quantum dots, as seen both in hBN and TMDs 10,[33][34][35] .…”

Section: Defect-assisted Tunneling At Zero Magnetic Fieldmentioning

confidence: 99%

Quantum-Dot Assisted Spectroscopy of Degeneracy-Lifted Landau Levels in Graphene

Keren,

Dvir,

Zalic

et al. 2020

Preprint

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Energy spectroscopy of strongly interacting phases requires probes which minimize screening while retaining spectral resolution and local sensitivity. Here we demonstrate that such probes can be realized using atomic sized quantum dots bound to defects in hexagonal Boron Nitride tunnel barriers, placed at nanometric distance from graphene. With dot energies capacitively tuned by a planar graphite electrode, dot-assisted tunneling becomes highly sensitive to the graphene excitation spectrum.The spectra track the onset of degeneracy lifting with magnetic field at the ground state, and at unoccupied exited states, revealing symmetry-broken gaps which develop steeply with magnetic field -corresponding to Landé g factors as high as 160. Measured up to B = 33 T, spectra exhibit a primary energy split between spin-polarized excited states, and a secondary spin-dependent valley-split. Our results show that defect dots probe the spectra while minimizing local screening, and are thus exceptionally sensitive to interacting states.

show abstract

Tunneling in Graphene/h-BN/Graphene Heterostructures through Zero-Dimensional Levels of Defects in h-BN and Their Use as Probes to Measure the Density of States of Graphene

Cited by 8 publications

References 26 publications

Quantum-dot assisted spectroscopy of degeneracy-lifted Landau levels in graphene

Quantum-dot assisted spectroscopy of degeneracy-lifted Landau levels in graphene

A magnetically-induced Coulomb gap in graphene due to electron-electron interactions

Quantum-Dot Assisted Spectroscopy of Degeneracy-Lifted Landau Levels in Graphene

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