Interplay of Fermi velocities and healing lengths in two-band superconductors

Chen, Yajiang; Zhu, Haiping; Shanenko, A. A.

doi:10.1103/physrevb.101.214510

Cited by 6 publications

(13 citation statements)

References 45 publications

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“…Now we turn to the case of strongly coupled condensates. Based on the previous studies [31][32][33] , we know that the difference between the gap-function lengths ξ ∆1 and ξ ∆2 decreases with increasing g 12 (at a constant ratio v F 2 /v F 1 ). Then, one expects that in the case of strongly coupled bands the gap-function lengths should be close to one another, as the system approaches the locking regime.…”

Section: A Numerical Results Of the Bdg Equationsmentioning

confidence: 88%

“…Further details of the numerical procedure can be found in the Supplemental Material and also in Ref. 33.…”

Section: B Bogoliubov-de Gennes Equations and Single Vortex Solutionmentioning

confidence: 99%

“…This value depends on the temperature T and the ratio of the band Fermi velocities v F 2 /v F 1 . One finds 32,33 that g * 12 drops significantly near T c and for the ratio v F 2 /v F 1 close to 1. Therefore, the two-band superconductors tend to be in the locking regime when approaching T c or in the case with nearly the same band Fermi velocities.…”

Section: Introductionmentioning

confidence: 98%

“…31 suggest that these materials can be in the so-called locking regime at which ξ ∆1 and ξ ∆2 are nearly the same. Microscopic calculations for clean two-band systems 32,33 demonstrate that this regime takes place when the interband (pairexchange) coupling g 12 exceeds its locking value g * 12 . This value depends on the temperature T and the ratio of the band Fermi velocities v F 2 /v F 1 .…”

Section: Introductionmentioning

confidence: 99%

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Multiband Superconductors: Two Characteristic Lengths for Each Contributing Condensate

Chen¹,

Shanenko²

2022

Preprint

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Traditionally, the characteristic length of a superconducting condensate is associated with the spatial distribution of the corresponding gap function. However, the superconducting condensate is the quantum condensate of Cooper pairs and thus, the broader readership is more familiar with the concept of the Cooper-pair wave function. For conventional single-band superconductors, the gap function coincides with the center-of-mass wave function of a Cooper pair up to the coupling constant, and the corresponding gap-and wave-function characteristic lengths are the same. Surprisingly, we find that in two-band superconductors, these lengths are the same only near the critical temperature. At lower temperatures they can significantly deviate from each other, and the question arises as to which of these lengths should be given the preference when specifying the spatial scale of the band-dependent condensate in multiband superconducting materials.

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Section: A Numerical Results Of the Bdg Equationsmentioning

confidence: 88%

“…Further details of the numerical procedure can be found in the Supplemental Material and also in Ref. 33.…”

Section: B Bogoliubov-de Gennes Equations and Single Vortex Solutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Multiband Superconductors: Two Characteristic Lengths for Each Contributing Condensate

Chen¹,

Shanenko²

2022

Preprint

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“…The disconnected multiband nature with very distinct orbital projections, Fermi velocities, and nesting vectors support two-band superconductivity conjecture in this system [56,68,[71][72][73][74][75], consistently with the experimental findings. In fact, the different band Fermi velocities of ZrTe 2 favors the emergence of such unconventional superconducting magnetic properties due to the presence of multiple condensates with dissimilar compet-ing characteristic lenghts [76].…”

Section: B Cdw and Superconductivity Interplay: First-principles Calc...mentioning

confidence: 99%

Evidence for multiband superconductivity and charge density waves in Ni-doped ZrTe$_2$

Correa,

Ferreira,

de Faria

et al. 2021

Preprint

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We carried out a comprehensive study of the electronic, magnetic, and thermodynamic properties of Ni-doped ZrTe2. High quality Ni0.05ZrTe2 single crystals show the coexistence of charge density waves (CDW, TCDW ≈ 287 K) with superconductivity (Tc ≈ 4.1 K), which we report here for the first time. The temperature dependence of the lower (Hc 1 ) and upper (Hc 2 ) critical magnetic fields both deviate significantly from the behaviors expected in conventional single-gap s-wave superconductors. However, the behaviors of the normalized superfluid density ρs(T ) and Hc 2 (T ) can be described well using a two-gap model for the Fermi surface, in a manner consistent with multiband superconductivity. Electrical resistivity and specific heat measurements show clear anomalies centered near 287 K, suggestive of CDW phase transition. Additionally, electronic structure calculations support the coexistence of electron-phonon multiband superconductivity and CDW due to the compensated disconnected nature of the electron-and hole-pockets at the Fermi surface, with very distinct orbital characters, Fermi velocities, and nesting vectors, as well as the softening of the acoustic phonon modes. Our calculations also suggest that ZrTe2 is a non-trivial topological type-II Dirac semimetal. These findings highlight that Ni-doped ZrTe2 is uniquely important for probing the coexistence of superconducting and CDW ground states in an electronic system with non-trivial topology.

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Multiband Superconductors: Two Characteristic Lengths for Each Contributing Condensate

Chen

Shanenko

2022

J. Phys. Chem. Lett.

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The interference of multiple condensates coexisting in one system may lead to unconventional coherent behavior. This is expected when the spatial lengths of the condensates are essentially different. Traditionally, the characteristic spatial length of a superconducting condensate is associated with the gap function. However, the broader readership is more familiar with the concept of the Cooper-pair wave function. For conventional single-band superconductors, the gap function coincides with the center-of-mass Cooper-pair wave function up to the coupling constant, and the corresponding gap and wave function characteristic lengths are the same. Surprisingly, we find that in two-band superconductors, these lengths are the same only near the critical temperature. At lower temperatures, they can significantly deviate from each other, and the fundamental question of which of these lengths should be preferred when specifying the spatial scale of a band-dependent condensate in multiband superconducting materials arises.

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Interplay of Fermi velocities and healing lengths in two-band superconductors

Cited by 6 publications

References 45 publications

Multiband Superconductors: Two Characteristic Lengths for Each Contributing Condensate

Multiband Superconductors: Two Characteristic Lengths for Each Contributing Condensate

Evidence for multiband superconductivity and charge density waves in Ni-doped ZrTe$_2$

Multiband Superconductors: Two Characteristic Lengths for Each Contributing Condensate

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