<i>Ab initio</i>theory of superconductivity. I. Density functional formalism and approximate functionals

Lüders, M.; Marques, Miguel A. L.; Lathiotakis, N. N.; Floris, Andrea; Profeta, G.; Fast, Lars; Continenza, A.; Massidda, S.; Gross, E. K. U.

doi:10.1103/physrevb.72.024545

Cited by 360 publications

(233 citation statements)

References 47 publications

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“…All superconductivity calculations are performed within SCDFT [66,67]. The approximations used have been described in previous works [10,15,51,68,69].…”

Section: B Coupling and Superconductivity Calculationsmentioning

confidence: 99%

Interplay between structure and superconductivity: Metastable phases of phosphorus under pressure

Flores‐Livas

Sanna

Дроздов

et al. 2017

Phys. Rev. Materials

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Pressure-induced superconductivity and structural phase transitions in phosphorus (P) are studied by resistivity measurements under pressures up to 170 GPa and by fully ab initio crystal structure exploration and superconductivity calculations up to 350 GPa. Two distinct superconducting transition temperature (T C ) vs pressure (P ) trends at low pressure have been reported more than 30 years ago, and we are able to devise a consistent explanation founded on thermodynamically metastable phases of black phosphorus. Our experimental and theoretical results form a single, consistent picture which not only provides a clear understanding of elemental P under pressure but also sheds light on the longstanding and unsolved anomalous superconductivity trends. Moreover, at higher pressures we predict a similar scenario of multiple metastable structures which coexist beyond their thermodynamical stability range. We observe that all the metastable structures systematically exhibit larger transition temperatures than the ground-state structures, indicating that the exploration of metastable phases represents a promising route to design materials with improved superconducting properties.

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“…All superconductivity calculations are performed within SCDFT [66,67]. The approximations used have been described in previous works [10,15,51,68,69].…”

Section: B Coupling and Superconductivity Calculationsmentioning

confidence: 99%

Interplay between structure and superconductivity: Metastable phases of phosphorus under pressure

Flores‐Livas

Sanna

Дроздов

et al. 2017

Phys. Rev. Materials

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“…It would be desirable to perform first principles calculations of the superconducting gap including electronelectron effects as in the density functional theory for superconductors (SCDFT) 58,59 , however the incorporation of such effects in the ME theory is nontrivial. As a simpler alternative we estimate µ * c using the model screened Coulomb interaction proposed in Ref.…”

Section: Coulomb Effectsmentioning

confidence: 99%

Two-gap superconductivity in heavilyn-doped graphene:Ab initioMigdal-Eliashberg theory

Margine

Giustino

2014

Phys. Rev. B

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Graphene is the only member of the carbon family from zero-to three-dimensional materials for which superconductivity has not been observed yet. At this time, it is not clear whether the quest for superconducting graphene is hindered by technical challenges, or else by the fluctuation of the order parameter in two dimensions. In this area, ab initio calculations are useful to guide experimental efforts by narrowing down the search space. In this spirit, we investigate from first principles the possibility of inducing superconductivity in doped graphene using the fully anisotropic MigdalEliashberg theory powered by Wannier-Fourier interpolation. To address a best-case scenario, we consider both electron and hole doping at high carrier densities, so as to align the Fermi level to a van Hove singularity. In these conditions, we find superconducting gaps of s−wave symmetry, with a slight anisotropy induced by the trigonal warping, and, in the case of n-doped graphene, an unexpected two-gap structure reminiscent of MgB2. Our Migdal-Eliashberg calculations suggest that the observation of superconductivity at low temperature should be possible for n-doped graphene at carrier densities exceeding 10 15 cm −2 .

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“…by inverse photoemission or high resolution X-ray absorption) complementing the published ARPES measurements [51] , would help to confirm the presence of an empty impurity band and/or deep inactive boron-related levels in order to understand the coupling mechanisms and the relation between impurity and free carrier concentrations. c) Calculations of T C and 2∆(Τ) within the recently developed density functional theory for superconductors [95,96] will suppress the need to adjust the µ* value. This approach was tested on several simple materials showing excellent agreement with experimental transition temperatures and quasiparticle band gaps.…”

Section: ) Conclusion and Open Questionsmentioning

confidence: 99%

Superconducting group-IV semiconductors

et al. 2009

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We present recent achievements and predictions in the field of doping-induced superconductivity in column IV-based covalent semiconductors, with a focus on Bdoped diamond and silicon. Despite the amount of experimental and theoretical work produced over the last four years, many open questions and puzzling results remain to be clarified. The nature of the coupling (electronic correlation and/or phonon-mediated), the relationship between the doping concentration and the critical temperature (T C ), which determines the prospects for higher transition temperatures, as well as the influence of disorder and dopant homogeneity, are debated issues that will determine the future of the field. We suggest that innovative superconducting devices, combining specific properties of diamond or silicon, and the maturity of semiconductor-based technologies, will soon be developed. 1) IntroductionIt was probably the discovery of a superconducting transition around 40 K in the rather simple MgB 2 compound [1] that revived the interest for a specific class of superconducting materials, belonging to the so-called covalent metals [2] . These superconducting covalent systems (see box 1), including B-doped diamond [3] , silicon [4] , and silicon carbide [5,6] , Ba-doped silicon clathrates [7,8] , alkali-doped fullerenes [9,10] and the CaC 6 or YbC 6 intercalated graphites [11,12] , share the specificity of involving at least one relatively light element and of preserving strongly directional covalent bonds in their metallic state. The implications of this covalent character are important in superconductors in which Cooper pairs are coupled through phonons. The use of perturbation theory to study the renormalisation of the electron-electron repulsion by the electron-phonon interaction leads to the so-called Eliashberg equations [13] and to the celebrated McMillan formula [13] relating, in an approximate way, the superconducting transition temperature T C to an average phonon frequency ω ln , the electron-phonon coupling parameter λ ep and the screened and retarded Coulomb repulsion parameter µ*: Clearly, low atomic masses lead to high frequency phonon modes, which may enhance the ω ln prefactor and thus T C . This is the basis of the so-called isotope effect. Furthermore, strong covalent bonding will lead both to large phonon frequencies and a large electron-phonon coupling potential V ep =λ ep /N(E F ), with N(E F ) the density of states at the Fermi level, also contributing to enhance T C . Even within a phonon-mediated coupling scenario, these criteria do not necessarily warrant a large T C since increasing λ ep may also lead to a lattice instability, and a large electron-phonon potential V ep may be impaired by a low density N(E F ). However, these simple considerations, as well as more elaborate surveys and predictions of a larger T C [14][15][16] , have provided much incentive to study this class of materials.The most familiar covalent systems are certainly diamond and silicon. The former can be considered as the prototype insula...

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Ab initiotheory of superconductivity. I. Density functional formalism and approximate functionals

Cited by 360 publications

References 47 publications

Interplay between structure and superconductivity: Metastable phases of phosphorus under pressure

Interplay between structure and superconductivity: Metastable phases of phosphorus under pressure

Two-gap superconductivity in heavilyn-doped graphene:Ab initioMigdal-Eliashberg theory

Superconducting group-IV semiconductors

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