van der Waals heterostructures combining graphene and hexagonal boron nitride

Yankowitz, Matthew; Ma, Qiong; Jarillo‐Herrero, Pablo; LeRoy, Brian J.

doi:10.1038/s42254-018-0016-0

Cited by 372 publications

(279 citation statements)

References 127 publications

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“…Most studies employ them for demonstrating 2D devices, and a variety of outstanding properties and applications of atomically thin 2D materials have been reported. 7 For all the success of the HPHT single crystals for 2D physics, there is still room for improvement of the HPHT crystals. One issue is the potential problem of an invisible impurity domain.…”

Section: Introductionmentioning

confidence: 99%

Far-UV photoluminescence microscope for impurity domain in hexagonal-boron-nitride single crystals by high-pressure, high-temperature synthesis

Watanabe

Taniguchi

2019

npj 2D Mater Appl

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Hexagonal-boron-nitride single crystals grown by high-pressure, high-temperature (HPHT) synthesis are commonly used as the insulated substrate dielectric for two-dimensional (2D) atomic-layered materials like graphene and transition metal dichalcogenides (TMDs) to improve the flatness of the 2D materials atomically without disturbing the 2D electronic characteristics. However, HPHT single crystals often contain impure regions, which can hold subtle clues in regard to the 2D atomic-layered materials for new discoveries in the physics of 2D materials. To identify the position of the impure domains and to avoid them when the 2D devices are prepared, a far-ultraviolet photoluminescence microscope was developed. This microscope makes it possible to visualize the impure-growth region with ease in a no-contact and non-destructive manner. npj 2D Materials and Applications (2019) 3:40; https://doi.

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Section: Introductionmentioning

confidence: 99%

Far-UV photoluminescence microscope for impurity domain in hexagonal-boron-nitride single crystals by high-pressure, high-temperature synthesis

Watanabe

Taniguchi

2019

npj 2D Mater Appl

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“…Behavior of ballistic electrons in a uniform material resembles that of photons to a high degree [1][2][3][4][5][6][7]35]. For example, electrons follow straight trajectories when considered as particles [16][17][18], while interference effects, such as the Aharonov-Bohm [19][20][21] and Fabry-Perot effects [22], are caused by their wave nature.…”

Section: Main Textmentioning

confidence: 99%

Electron-hole hybridization in bilayer graphene

Wang

Zhao

Zhang

et al. 2019

National Science Review

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Band structure determines the motion of electrons in a solid, giving rise to exotic phenomena when properly engineered. Drawing an analogy between electrons and photons, artificially designed optical lattices indicate the possibility of a similar band modulation effect in graphene systems. Yet due to the fermionic nature of electrons, modulated electronic systems promise far richer categories of behaviors than those found in optical lattices. Here, we uncovered a strong modulation of electronic states in bilayer graphene subject to periodic potentials. We observed for the first time the hybridization of electron and hole sub-bands, resulting in local band gaps at both primary and secondary charge neutrality points. Such hybridization leads to the formation of flat bands, enabling the study of correlated effects in graphene systems. This work may also offer a viable platform to form and continuously tune Majorana zero modes, which is important to the realization of topological quantum computation. Main textBehavior of ballistic electrons in a uniform material resembles that of photons to a high degree [1][2][3][4][5][6][7]35]. For example, electrons follow straight trajectories when considered as particles [16][17][18], while interference effects, such as the Aharonov-Bohm [19][20][21] and Fabry-Perot effects [22], are caused by their wave nature. Due to the conservation of the transverse momentum and the Fermi energy, electron propagation at the boundary of two regions with different carrier densities is subject to reflection and refraction in a way similar to optical rays crossing the boundary of two materials with different refractive indices [23]. Unlike photons, electrons in an atomically thin material can be efficiently manipulated by an artificially designed and applied potential profile that controls the spatial carrier density profile [24][25][26], resulting in graphene electron optics. This opened the way to realizing scenarios that are typically difficult to achieve by traditional optics,

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“…The development of van der Waals heterostructures designed from two-dimensional materials [23][24][25] in addition to the recent progresses in sample fabrication 26,27 , dramatically improved both charge carrier mobility and contact transparency in graphene-based electrical devices. As a consequence, the study of proximity induced superconductivity regained interest with the possibilities to measure large supercurrents and ballistic interferences [28][29][30][31][32][33][34][35][36][37][38][39][40][41] .…”

Section: Introductionmentioning

confidence: 99%

Andreev reflection in ballistic normal metal/graphene/superconductor junctions

et al. 2019

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We report the study of ballistic transport in normal metal/graphene/superconductor junctions in edge-contact geometry. While in the normal state, we have observed Fabry-Pérot resonances suggesting that charge carriers travel ballistically, the superconducting state shows that the Andreev reflection at the graphene/superconductor interface is affected by these interferences. Our experimental results in the superconducting state have been analyzed and explained with a modified Octavio-Tinkham-Blonder-Klapwijk model taking into account the magnetic pair-breaking effects and the two different interface transparencies, i.e. between the normal metal and graphene, and between graphene and the superconductor. We show that the transparency of the normal metal/graphene interface strongly varies with doping at large scale, while it undergoes weaker changes at the graphene/superconductor interface. When a cavity is formed by the charge transfer occurring in the vicinity of the contacts, we see that the transmission probabilities follow the normal state conductance highlighting the interplay between the Andreev processes and the electronic interferometer.

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van der Waals heterostructures combining graphene and hexagonal boron nitride

Cited by 372 publications

References 127 publications

Far-UV photoluminescence microscope for impurity domain in hexagonal-boron-nitride single crystals by high-pressure, high-temperature synthesis

Far-UV photoluminescence microscope for impurity domain in hexagonal-boron-nitride single crystals by high-pressure, high-temperature synthesis

Electron-hole hybridization in bilayer graphene

Andreev reflection in ballistic normal metal/graphene/superconductor junctions

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