Superconductivity in Quantum Complex Matter: the Superstripes Landscape

Bianconi, A.

doi:10.1007/s10948-020-05602-2

Cited by 4 publications

(3 citation statements)

References 122 publications

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“…The phase diagram is complex (pseudo-gap, charge density waves, stripes, checkerboard patterns, etc. [49,50]); however, those phases should be related to characteristics of the pristine La 2 CuO 4 phase. La 2 CuO 4 is an insulating antiferromagnet of Mott or rather charge-transfer type, in which the lowest excitation involves the gap between the oxygen-character band and the upper Hubbard band: O 2− + Cu 2+ → O − + Cu + .…”

Section: Underdoped Cupratesmentioning

confidence: 99%

Are Superconductivity Mechanisms a Matter for Chemists?

Villesuzanne

2020

Condensed Matter

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From a tight-binding approach to the instability of nonbonding electronic states, along a double-well potential, we consider here how the coupling of these states with a phonon mode can open a superconducting gap at the Fermi level. The alternation of broken- and unbroken-symmetry states, along the phonon breathing distortion, induces the mixing of band-edge states on a very short timescale, according to the noncrossing rule of chemists. We show that this mixing may generate cationic and anionic disproportionation. The negative U mechanism is thus justified here, leading to the mixing of occupied and unoccupied pair states, for the opening of a 2Δ superconducting gap. The closeness of broad σ * and narrow π * bands in the vicinity of the Fermi level should favor the superconducting phase over the insulating or metallic state, in agreement with Micnas et al.’s studies. We applied this approach to several families of superconducting materials, i.e., doped strontium titanate, high-TC cuprates and iron selenide.

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Section: Underdoped Cupratesmentioning

confidence: 99%

Are Superconductivity Mechanisms a Matter for Chemists?

Villesuzanne

2020

Condensed Matter

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“…The key feature of the BPV theory is the calculation of the energy dependent pair-transfer exchange interaction, which generates the Fano-Feshbach resonance in the Bogoliubov multi-gap superconductivity theory [52] [53]. The energy dependent pair-transfer exchange term is calculated from the overlap of the four wave-functions of the two-electron pairs at the two Fermi levels as obtained from the solution of the Schrödinger equation [11,12,[25][26][27][28][54][55][56][57][58][59][60] or the Dirac equation [61] for the particular nanoscale superlattice in the real space. This provides the line-shape of the T c amplification by Fano-Feshbach resonance due to configuration interaction between different pairing channels in the two-gap superconductivity in artificial superlattices of quantum wires and quantum wells which is missing in the singlegap BCS theory.…”

Section: Introductionmentioning

confidence: 99%

Spin–orbit coupling controlling the superconducting dome of artificial superlattices of quantum wells

Mazziotti

Bianconi

Raimondi

et al. 2022

Journal of Applied Physics

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While it is known that a resonant amplification of [Formula: see text] in two-gap superconductors can be driven by using the Fano–Feshbach resonance tuning the chemical potential near a Lifshitz transition, little is known on tuning the [Formula: see text] resonance by cooperative interplay of the Rashba spin–orbit coupling (RSOC) joint with phonon mediated (e-ph) pairing at selected k-space spots. Here, we present first-principles quantum calculation of superconductivity in an artificial heterostructure of metallic quantum wells with 3 nm period where quantum size effects give two-gap superconductivity with RSOC controlled by the internal electric field at the interface between the nanoscale metallic layers intercalated by insulating spacer layers. The key results of this work show that fundamental quantum mechanics effects including RSCO at the nanoscale [Mazziotti et al., Phys. Rev. B, 103, 024523 (2021)] provide key tools in applied physics for quantitative material design of unconventional high temperature superconductors at ambient pressure. We discuss the superconducting domes where [Formula: see text] is a function of either the Lifshitz parameter ([Formula: see text]) measuring the distance from the topological Lifshitz transition for the appearing of a new small Fermi surface due to quantum size effects with finite spin–orbit coupling and the variable e-ph coupling [Formula: see text] in the appearing second Fermi surface linked with the energy softening of the cut off [Formula: see text].

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“…Shape Resonances have been used to explain other phenomena. For instance, A Bianconi et al [31] were able to explain the dome shaped variation of the critical temperature upon doping observed in high-T c materials with a layered structure [32].…”

Section: Introductionmentioning

confidence: 99%

Shape resonances and the T _c dependence on film thickness of Ni/Bi systems

Doria¹,

Liu²,

Xing³

et al. 2021

Supercond. Sci. Technol.

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We report on the experimentally observed variation of the superconducting critical temperature (T c ) of Ni/Bi systems as a function of the total deposited film thickness and on its explanation using a theoretical model. Two series of Ni/Bi systems have been analyzed which were obtained by depositions of Ni onto Bi in the proportions Ni3Bix (3 nm of Ni onto x nm of Bi) and NiyBi6y (y nm Ni onto 6 y nm of Bi). As shown recently, the formation of the superconducting compound NiBi3 at Ni/Bi interfaces in the resulting NiBi3-Bi films is thermodynamically favored by a volume contraction. Here we corroborate this result and estimate the thickness of the resulting NiBi3 and of the remaining Bi layers for the Ni3Bix and NiyBi6y series using the laws of mass and conservation of number of atoms. We consider the resulting film as being made up of two homogeneous and uniform layers of NiBi3 and Bi, respectively, and study this idealizing model using the Bogoliubov de Gennes (BdG) equations. It is assumed that superconductivity originates in the NiBi3 layer and penetrates the Bi layers via a potential barrier. Our theoretical calculations predict the dependence of T c with respect to the thicknesses of the NiBi3 and Bi layers, and also with the strength of the potential barrier that blocks the migration of electrons from the NiBi3 to the Bi layer. The calculations show that the superconducting gap also exists in Bi, although much weaker than in the NiBi3 layer. We compare the predicted T c values with the experimental data and find sufficient agreement to suggest that our model can explain the experimentally observed variation of T c with thickness. We interpret this dependence as shape resonance oscillations which are derived from the BdG theory applied to thin superconducting films.

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Superconductivity in Quantum Complex Matter: the Superstripes Landscape

Cited by 4 publications

References 122 publications

Are Superconductivity Mechanisms a Matter for Chemists?

Are Superconductivity Mechanisms a Matter for Chemists?

Spin–orbit coupling controlling the superconducting dome of artificial superlattices of quantum wells

Shape resonances and the T _c dependence on film thickness of Ni/Bi systems

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Superconductivity in Quantum Complex Matter: the Superstripes Landscape

Cited by 4 publications

References 122 publications

Are Superconductivity Mechanisms a Matter for Chemists?

Are Superconductivity Mechanisms a Matter for Chemists?

Spin–orbit coupling controlling the superconducting dome of artificial superlattices of quantum wells

Shape resonances and the T c dependence on film thickness of Ni/Bi systems

Contact Info

Product

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Shape resonances and the T _c dependence on film thickness of Ni/Bi systems