Tuning superconductivity in twisted bilayer graphene

Yankowitz, Matthew; Chen, S.; Polshyn, Hryhoriy; Zhang, Y.; Watanabe, Kenji; Taniguchi, Takashi; Graf, David; Young, Andrea; Dean, Cory

doi:10.1126/science.aav1910

Cited by 2,032 publications

(1,941 citation statements)

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“…Experimentally, the “magic angle” graphene with a small amount of electrons can present a superconducting state at the temperature of 1.7 K (Figure e) . That means one can regulate TBG between insulators and superconductors . In addition, more different angles of TBG can be created and more physical phenomena could be explored in a single device .…”

Section: Introductionmentioning

confidence: 99%

Bilayer Graphene: From Stacking Order to Growth Mechanisms

Guan

Yuan

Luo

2020

Physica Rapid Research Ltrs

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Due to the unique bandgap tunability of bilayer graphene, the preparation of large‐sized bilayer graphene has attracted a wide range of attention. Herein, the preparation of bilayer graphene, from stacking order to growth mechanism, is reviewed, and the chemical vapor deposition (CVD) of AB‐stacked bilayer graphene on copper substrate is emphasized. Various methods and growth strategies to synthesize bilayer graphene and the corresponding growth mechanisms are discussed. Mechanisms of layer‐by‐layer growth, the hydrogen passivation of graphene edges for the formation of bilayers, and carbon atoms penetrating through a copper wall for bilayer growth are included and highlighted for a better understanding of controlling bilayer graphene uniformity and forming its stacking order. Finally, the remaining challenges and the potential development of CVD‐controlled growth of bilayer graphene are outlined.

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Section: Introductionmentioning

confidence: 99%

Bilayer Graphene: From Stacking Order to Growth Mechanisms

Guan

Yuan

Luo

2020

Physica Rapid Research Ltrs

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“…The insulating states, believed to be due to electronic correlations [1], were originally observed when the charge per moiré cell is ±2 with respect to the charge neutrality point (CNP). More recently, insulating states when the twisted bilayer graphene (TBG) is doped with 1 or 3 carriers have also been observed [2,3].…”

Section: Introductionmentioning

confidence: 99%

The nature of correlations in the insulating states of twisted bilayer graphene

Pizarro¹,

Calderón²,

Bascones³

2019

J. Phys. Commun.

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The recently observed superconductivity in twisted bilayer graphene emerges from insulating states believed to arise from electronic correlations. While there have been many proposals to explain the insulating behaviour, the commensurability at which these states appear suggests that they are Mott insulators. Here we focus on the insulating states with ±2 electrons or holes with respect to the charge neutrality point. We show that the theoretical expectations for the Mott insulating states are not compatible with the experimentally observed dependence on temperature and magnetic field if, as frequently assumed, only the correlations between electrons on the same site are included. We argue that the inclusion of non-local (inter-site) correlations in the treatment of the Hubbard model can bring the predictions for the magnetic and temperature dependencies of the Mott transition to an agreement with experiments and have consequences for the critical interactions, the size of the gap, and possible pseudogap physics. The importance of the inter-site correlations to explain the experimental observations indicates that the observed insulating gap is not the one between the Hubbard bands and that antiferromagnetic-like correlations play a key role in the Mott transition.

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“…Experimentalists are able to isolate layers of different materials only one‐atom, or few‐atoms, thick, and to combine such layers with increasing control of the stacking configuration. A striking example of this tunability is the recent experimental realization of vdW systems formed by two graphene layers in which the stacking angle, twist angle, can be adjusted to within a fraction of a degree . These experiments have shown that, by tuning the relative twist angle between graphene layers, the system can become superconducting or insulating.…”

Section: Introductionmentioning

confidence: 99%

“…A striking example of this tunability is the recent experimental realization of vdW systems formed by two graphene layers in which the stacking angle, twist angle, can be adjusted to within a fraction of a degree . These experiments have shown that, by tuning the relative twist angle between graphene layers, the system can become superconducting or insulating. These remarkable results are just one example of the ways in which vdW heterostructures can be used to realize electronic systems with exotic and desirable properties.…”

Section: Introductionmentioning

confidence: 99%

Van Der Waals Heterostructures with Spin‐Orbit Coupling

Rossi

Triola

2019

Annalen der Physik

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Herein, recent work on van der Waals (vdW) systems in which at least one of the components has strong spin‐orbit coupling is reviewed, focussing on a selection of vdW heterostructures to exemplify the type of interesting electronic properties that can arise in these systems. First a general effective model to describe the low energy electronic degrees of freedom in these systems is presented. The model is then applied to study the case of (vdW) systems formed by a graphene sheet and a topological insulator. The electronic transport properties of such systems are discussed and it is shown how they exhibit much stronger spin‐dependent transport effects than isolated topological insulators. Then, vdW systems are considered in which the layer with strong spin‐orbit coupling is a monolayer transition metal dichalcogenide (TMD) and graphene‐TMD systems are briefly discussed. In the second part of the article, a case is discussed in which the vdW system includes a superconducting layer in addition to the layer with strong spin‐orbit coupling. It is shown in detail how these systems can be designed to realize odd‐frequency superconducting pair correlations. Finally, twisted graphene‐NbSe2 bilayer systems are discussed as an example in which the strength of the proximity‐induced superconducting pairing in the normal layer, and its Ising character, can be tuned via the relative twist angle between the two layers forming the heterostructure.

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Tuning superconductivity in twisted bilayer graphene

Cited by 2,032 publications

References 84 publications

Bilayer Graphene: From Stacking Order to Growth Mechanisms

Bilayer Graphene: From Stacking Order to Growth Mechanisms

The nature of correlations in the insulating states of twisted bilayer graphene

Van Der Waals Heterostructures with Spin‐Orbit Coupling

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