Superconductivity in Ca-intercalated epitaxial graphene on silicon carbide

Li, Kang; Feng, Xiao; Zhang, Wenhao; Ou, Yunbo; Chen, Lianlian; He, Ke; Wang, Lili; Guo, Liwei; Liu, Guodong; Xue, Quan; Ma, Xu-Cun

doi:10.1063/1.4817781

Cited by 63 publications

(52 citation statements)

References 21 publications

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“…With Ge used as intercalant, it was possible to generate three types of regions: pristine, n-doped (1-layer Ge), and p-doped (2-layer Ge) areas that have potential use as in-plane transistors [63,64,185,186]. Superconductivity in Ca-intercalated multilayer epitaxial graphene films on SiC has also been reported [187]. Transition metal [71,72] intercalation (e.g., Co on G1/Ir(1 1 1)) was also shown to have dramatic effects on the magnetic properties of graphene [188].…”

Section: Intercalation For Supported Graphene Systems and For Graphitementioning

confidence: 95%

Growth morphology and properties of metals on graphene

Liu

Han

Evans

et al. 2015

Progress in Surface Science

145

125

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a b s t r a c tGraphene, a single atomic layer of graphite, has been the focus of recent intensive studies due to its novel electronic and structural properties. Metals grown on graphene also have been of interest because of their potential use as metal contacts in graphene devices, for spintronics applications, and for catalysis. All of these applications require good understanding and control of the metal growth morphology, which in part reflects the strength of the metal-graphene bond. Also of importance is whether the interaction between graphene and metal is sufficiently strong to modify the electronic structure of graphene. In this review, we will discuss recent experimental and computational studies related to deposition of metals on graphene supported on various substrates (SiC, SiO 2 , and hexagonal close-packed metal surfaces). Of specific interest are the metal-graphene interactions (adsorption energies and diffusion barriers of metal adatoms), and the crystal structures and thermal stability of the metal nanoclusters.

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Section: Intercalation For Supported Graphene Systems and For Graphitementioning

confidence: 95%

Growth morphology and properties of metals on graphene

Liu

Han

Evans

et al. 2015

Progress in Surface Science

145

125

View full text Add to dashboard Cite

show abstract

“…In contrast, nearly all allotropes of carbon including fullerenes, nanotubes, diamond and graphite were shown to exhibit superconductivity under heavy doping 7 8 9 10 . Interest in carbon-based superconductors has recently 11 12 13 been revived by the discovery of superconductivity in CaC 6 , Ca-intercalated graphite compound (Ca-GIC) with T c ≈ 11.5 K. Although some aspects of its superconductivity remain under debate 14 15 16 17 18 , main contributing factors have been identified 14 15 17 as (i) doping via metal adatoms to reach sufficiently high electron concentrations in graphite, (ii) importance of an interlayer (IL) electronic band that arises from the intercalant superlattice formed between graphene layers, and (iii) the overall electron-phonon coupling that is related to coupling involving graphene phonons and intercalant vibrations. According to recent DFT calculations 4 , similar conditions are required to induce superconductivity in metal decorated graphene, i.e.…”

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confidence: 99%

Superconductivity in Ca-doped graphene laminates

Chapman

Howard

et al. 2016

Sci Rep

127

102

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Despite graphene’s long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc’s strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp.

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“…Similar to bulk graphite, graphene itself is not superconducting because of the vanishingly small electronic density of states at the Fermi level, requiring modification of its electronic structure in order to facilitate superconductivity [1,2].Several efforts have been initiated to introduce a change in the band structure by depositing atoms or molecules on the graphene and through the application of an external electric field [4][5][6][7][8][9]. Recently, the intercalation of guest atoms into graphene layers in carbon allotropes has been reported to induce superconductivity [10][11][12], though which electronic states, intercalant-or graphene-derived, and which phonons are responsible for the superconducting Cooper pairing remains unclear [13][14][15][16][17].…”

mentioning

confidence: 99%

Superconductivity at 7.4 K in few layer graphene by Li-intercalation

Tiwari

Shin

Hwang

et al. 2017

J. Phys.: Condens. Matter

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Superconductivity in graphene has been highly sought after for its promise in various device applications and for general scientific interest. Ironically, the simple electronic structure of graphene, which is responsible for novel quantum phenomena, hinders the emergence of superconductivity. Theory predicts that doping the surface of the graphene effectively alters the electronic structure, thus promoting propensity towards Cooper pair instability (Profeta et al (2012) Nat. Phys. 8 131-4; Nandkishore et al (2012) Nat. Phys. 8 158-63) [1, 2]. Here we report the emergence of superconductivity at 7.4 K in Li-intercalated few-layer-graphene (FLG). The absence of superconductivity in 3D Li-doped graphite underlines that superconductivity in Li-FLG arises from the novel electronic properties of the 2D graphene layer. These results are expected to guide future research on graphene-based superconductivity, both in theory and experiments. In addition, easy control of the Li-doping process holds promise for various device applications.

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Superconductivity in Ca-intercalated epitaxial graphene on silicon carbide

Cited by 63 publications

References 21 publications

Growth morphology and properties of metals on graphene

Growth morphology and properties of metals on graphene

Superconductivity in Ca-doped graphene laminates

Superconductivity at 7.4 K in few layer graphene by Li-intercalation

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