Superconducting properties of lithium-decorated bilayer graphene

Szczęśniak, D.

doi:10.1209/0295-5075/111/18003

Cited by 8 publications

(5 citation statements)

References 40 publications

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“…Herein, we have conducted the analysis within the Migdal-Eliashberg formalism in order to account for the strong-coupling and phononmediated character of the superconducting phase in these graphene structures. In this manner, the presented study complements not only the work by Zhou et al [6] but also our previous investigations of the conventional superconductivity in graphene- [11,12,22,23] or generally carbon-based structures [24][25][26]. This is to say that the presented discussion constitutes a contribution to the wider research domain aimed at the search for a strong conventional superconducting phase in low-dimensional carbon structures.…”

Section: Discussionsupporting

confidence: 77%

Critical Field and Specific Heat in Electron- and Hole-Doped Graphene Superconductors

Drzazga-Szczęśniak

Kaczmarek

2023

Acta Phys. Pol. A

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Doping is one of the most prominent techniques to alter the properties of a given material. Herein, the influence of the electron-and hole-doping on the selected superconducting properties of graphene are considered. In detail, the Migdal-Eliashberg formalism is employed to analyze the specific heat and the critical magnetic field in the representative cases of graphene doped with nitrogen or boron. It is found that electron doping is much more favorable in terms of enhancing the aforementioned properties than its hole counterpart. These findings are appropriately summarized by means of the dimensionless thermodynamic ratios, familiar in the Bardeen-Cooper-Schrieffer theory. To this end, the perspectives for future research on superconductivity in graphene are drawn.

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Section: Discussionsupporting

confidence: 77%

Critical Field and Specific Heat in Electron- and Hole-Doped Graphene Superconductors

Drzazga-Szczęśniak

Kaczmarek

2023

Acta Phys. Pol. A

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“…In this manner our work appears as a supplementary to the already available studies, but also attempts to visualize discussed effects in the magnetic features of CaC 6 . Such complementary picture may be additionally of great importance for future studies on GICs as well as their purely two-dimensional counterparts like the lithium-decorated graphene [13][14][15][16], which is also predicted to present sizable anisotropy [17,18]. To this end, present work attempts to verify the postulate that six-band model of FS in CaC 6 should be considered as a minimal approximation [2].…”

Section: Introductionmentioning

confidence: 90%

Revealing the anisotropy effects on the critical magnetic field in CaC6 superconductor

2019

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The calcium intercalated graphite (CaC6) is considered to be a representative material of the graphite intercalated superconductors, which exhibits sizable anisotropy of the Fermi surface (FS). Herein, the influence of the FS anisotropy on the critical magnetic field (HC) in CaC6 superconductor is comprehensively analyzed within the Migdal-Eliashberg (M-E) formalism. To precisely account for the mentioned anisotropy effects, the analysis is conducted in the framework of the six-band approximation, hitherto not employed for calculations of the HC function in CaC6 material. For convenience, the obtained results are compared with the available one-and three-band estimates reported by using the M-E theory. A notable signatures of the increased number of bands are observed for the temperature dependent HC functions. In particular, the HC function decreases at T=0 K as the number of the considered bands is higher. Moreover, it is argued that the sixband formalism yields the most physically relevant shape of the HC function among all considered approximations. Therefore, the six-band model introduces not only quantitative but also qualitative changes to the results, in comparison to the other discussed FS approximations. This observation supports postulate that the six-band model constitutes minimal structure for FS of CaC6, but also magnify importance of anisotropy effects for the critical magnetic field calculations.

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“…Specifically, the Eliashberg formalism is employed in the isotopic form within the Migdal approximation [16], in correspondence to the isotropic approximation of pairing gap proposed in [10]. Herein, the Eliashberg equations are solved on the imaginary axis, and later analytically continued on the real axis, by using the numerical methods employed previously in [17][18][19][20][21]. The following form of the Eliashberg equations on the imaginary axis (i ≡ √ −1) is adopted during calculations:…”

Section: Resultsmentioning

confidence: 99%

Characterization of the superconducting phase in tellurium hydride at high pressure

et al. 2019

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At present, hydrogen-based compounds constitute one of the most promising classes of materials for applications as a phonon-mediated high-temperature superconductors. Herein, the behavior of the superconducting phase in tellurium hydride (HTe) at high pressure (p = 300 GPa) is analyzed in details, by using the isotropic Migdal-Eliashberg equations. The chosen pressure conditions are considered here as a case study which corresponds to the highest critical temperature value (Tc) in the analyzed material, as determined within recent density functional theory simulations. It is found that the Migdal-Eliashberg formalism, which constitutes a strong-coupling generalization of the Bardeen-Cooper-Schrieffer (BCS) theory, predicts that the critical temperature value (Tc = 52.73 K) is higher than previous estimates of the McMillan formula. Further investigations show that the characteristic dimensionless ratios for the the thermodynamic critical field, the specific heat for the superconducting state, and the superconducting band gap exceeds the limits of the BCS theory. In this context, also the effective electron mass is not equal to the bare electron mass as provided by the BCS theory. On the basis of these findings it is predicted that the strong-coupling and retardation effects play pivotal role in the superconducting phase of HTe at 300 GPa, in agreement with similar theoretical estimates for the sibling hydrogen and hydrogen-based compounds. Hence, it is suggested that the superconducting state in HTe cannot be properly described within the mean-field picture of the BCS theory.

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Superconducting properties of lithium-decorated bilayer graphene

Cited by 8 publications

References 40 publications

Critical Field and Specific Heat in Electron- and Hole-Doped Graphene Superconductors

Critical Field and Specific Heat in Electron- and Hole-Doped Graphene Superconductors

Revealing the anisotropy effects on the critical magnetic field in CaC6 superconductor

Characterization of the superconducting phase in tellurium hydride at high pressure

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