Vortex spectroscopy in the vortex glass: A real-space numerical approach

Berthod, Christophe

doi:10.1103/physrevb.94.184510

Cited by 15 publications

(30 citation statements)

References 69 publications

(155 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this Appendix we show that, in the BEC (strong-coupling) limit of the BCS-BEC crossover, whereby the fermionic BdG equations reduce to the bosonic Gross-Pitaevskii (GP) equation for the composite bosons that form in this limit [16], the (ρ −2 ) long-range behavior of the condensate wave function Φ(r) = m 2 a F 8π ∆(r) can be determined by simple analytic considerations. Although this result has already been reported for a vortex filament in an almost ideal Bose gas described at low temperature by the GP equation [29], the reason to briefly discuss it here is that its relevance for a vortex in a fermionic superfluid described by the BdG equations has passed essentially unnoticed in the literature [1,5,18].…”

Section: Appendix A: Internal Structure Of a Vortexmentioning

confidence: 67%

Bound states in a superfluid vortex: A detailed study along the BCS-BEC crossover

2019

View full text Add to dashboard Cite

The bound states that can occur in a superfluid vortex have recently called for attention owing to the capability of detecting them experimentally. However, a detailed theoretical account for the presence of these vortex bound states is still lacking, for all temperatures in the superfluid phase and couplings along the BCS-BEC crossover. Here, we fill this gap and present a systematic theoretical study based on the Bogoliubov-de Gennes equations for the bound states that occur over the two characteristic (inner and outer) spatial ranges in which the extension of a superfluid vortex can be partitioned. It is found that the total number of bound states decreases from the BCS (weak-coupling) side of the crossover toward the intermediate-coupling region where they are still present, whereas the bound states disappear upon entering the BEC (strong-coupling) side. A scaling relation is also obtained that connects the number of bound states in the inner spatial range of the vortex to the depth and width of the vortex itself. A criterion is finally provided in terms of the local density of states, to distinguish where a given fermionic superfluid is located in the coupling-temperature phase diagram of the BCS-BEC crossover.arXiv:1904.03883v1 [cond-mat.supr-con]

show abstract

Section: Appendix A: Internal Structure Of a Vortexmentioning

confidence: 67%

Bound states in a superfluid vortex: A detailed study along the BCS-BEC crossover

2019

View full text Add to dashboard Cite

show abstract

“…1(a), and in a finite magnetic field carry a Peierls phase (see, e.g., Ref. 23). The order parameter ∆ α r r is determined self-consistently from the pairing interaction V r r according to…”

Section: Model and Methodsmentioning

confidence: 99%

“…As the simulation uses a system ∼ 4 times larger than the field of view of that figure, we have generated random vortex positions outside the field of view with a distribution similar to that seen inside (Appendix G). The disordered vortices are surrounded by an ordered square lattice at the same field in order to ensure the correct boundary condition for an infinite distribution of vortices [23]. The unknown vortex positions outside the field of view do influence the LDOS calculated inside [7].…”

Section: Effects Of Chemical Disorder Density Inhomogeneity Andmentioning

confidence: 99%

“…Another possibility would be density inhomogeneities, which would locally change the balance between the electron and hole pockets. One could also adduce the irregular distribution of vortices observed in the experiments, as simulations have shown that disorder in the vortex positions impacts the local density of states (LDOS) in the cores [7,23].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Signatures of nodeless multiband superconductivity and particle-hole crossover in the vortex cores of FeTe0.55Se0.45

Berthod

2018

Phys. Rev. B

View full text Add to dashboard Cite

Scanning tunneling experiments on single crystals of superconducting FeTe 0.55 Se 0.45 have recently provided evidence for discrete energy levels inside vortices. Although predicted long ago, such levels are seldom resolved due to extrinsic (temperature, instrumentation) and intrinsic (quasiparticle scattering) limitations. We study a microscopic multiband model with parameters appropriate for FeTe 0.55 Se 0.45 . We confirm the existence of well-separated bound states and show that the chemical disorder due to random occupation of the chalcogen site does not affect significantly the vortex-core electronic structure. We further analyze the vortex bound states by projecting the local density of states on angular-momentum eigenstates. A rather complex pattern of bound states emerges from the multiband and mixed electron-hole nature of the normalstate carriers. The character of the vortex states changes from hole-like with negative angular momentum at low energy to electron-like with positive angular momentum at higher energy within the superconducting gap. We show that disorder in the arrangement of vortices most likely explains the differences found experimentally when comparing different vortices. arXiv:1808.08390v2 [cond-mat.supr-con]

show abstract

“…Note that this LDOS anisotropy is unrelated to the d-wave gap anisotropy. In the quantum regime k F ξ ∼ 1 relevant for Y123, the vortex size is comparable with the Fermi wavelength and the Fermisurface anisotropy determines the vortex structure [52,53]. In the Supplemental Material, Fig.…”

mentioning

confidence: 98%

Cuprate Superconductors May Be Conventional After All

Song

Xue

2017

Physics

View full text Add to dashboard Cite

The copper oxides present the highest superconducting temperature and properties at odds with other compounds, suggestive of a fundamentally different superconductivity. In particular, the Abrikosov vortices fail to exhibit localized states expected and observed in all clean superconductors. We have explored the possibility that the elusive vortex-core signatures are actually present but weak. Combining local tunneling measurements with large-scale theoretical modeling, we positively identify the vortex states in YBa 2 Cu 3 O 7−δ . We explain their spectrum and the observed variations thereof from one vortex to the next by considering the effects of nearby vortices and disorder in the vortex lattice. We argue that the superconductivity of copper oxides is conventional, but the spectroscopic signature does not look so because the superconducting carriers are a minority. DOI: 10.1103/PhysRevLett.119.237001 Type-II superconductors immersed in a magnetic field let quantized flux tubes perforate them: the Abrikosov vortices. This remarkable property underlies and often limits many applications of superconductors. In 1964, Caroli, de Gennes, and Matricon used the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity to predict that vortices in type-II superconductors host a collection of localized electrons bound to their cores [1]. The direct observation of these localized states 25 years later by scanning tunneling spectroscopy (STS) is a spectacular verification of the BCS theory [2]. The formation of vortex-core bound states is an immediate consequence of the superconducting condensate being composed of electron pairs, while excitations in the vortex, being unpaired, have a different topology. Core states are, therefore, a robust property of superconductors, like edge states in topological insulators, irrespective of the origin and symmetry of the force that glues the electrons into pairs. In spectroscopy, they appear in the clean limit l ≫ ξ as a zero-bias peak in the local density of states (LDOS) at the vortex center, where l and ξ are the electron mean free path and superconducting coherence length, respectively, or as a structureless LDOS in the dirty limit l ≲ ξ [3]. Next to NbSe 2 [2,4], the core states were seen by STS in several superconducting materials [5][6][7][8][9][10], including the pnictides, which are believed to host unconventional pairing [11][12][13][14][15]. The high-T c cuprates stand out as the only materials in which the vortex-core states have been looked for but not found. In YBa 2 Cu 3 O 7−δ (Y123), discrete finite-energy structures initially believed to be vortex states [16,17] were recently shown to be unrelated to vortices [18]. In Bi 2 Sr 2 CaCu 2 O 8þδ (Bi2212), the vortex cores present no trace of a robust zero-bias peak, but instead very weak finite-energy features apparently related to a charge-density wave order [19][20][21][22][23][24].The absence of vortex states in cuprates is challenging the existing theories. Because these states are topological they are robust [25...

show abstract

Vortex spectroscopy in the vortex glass: A real-space numerical approach

Cited by 15 publications

References 69 publications

Bound states in a superfluid vortex: A detailed study along the BCS-BEC crossover

Bound states in a superfluid vortex: A detailed study along the BCS-BEC crossover

Signatures of nodeless multiband superconductivity and particle-hole crossover in the vortex cores of FeTe0.55Se0.45

Cuprate Superconductors May Be Conventional After All

Contact Info

Product

Resources

About