Quantum Limiting Behaviors of a Vortex Core in an Anisotropic Gap Superconductor

Kaneko, Shigeo; Мацуба, К.; Hafiz, Muhammad; Yamasaki, Keigo; Kakizaki, Erika; Nishida, N.; Takeya, Hiroyuki; Hirata, Kazuto; Kawakami, Takuto; Mizushima, Takeshi; Machida, Kazushige

doi:10.1143/jpsj.81.063701

Cited by 35 publications

(43 citation statements)

References 20 publications

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“…[1][2][3][4] In the present case of Bi2212, tunneling spectra near the center of a vortex core still exhibit a clear energy gap, as can be seen in the spectrum at position Fig. 1( j)].…”

supporting

confidence: 51%

“…The behavior of the vortex core states expanding in space with increasing energy is the same as that of the vortex core bound states of s-wave superconductors. [1][2][3][4] As the electron-like and the hole-like vortex core states are observed at symmetric positions with respect to the Fermi energy and are modulated in space in antiphase with each other, they have the characteristics of Bogoliubov quasiparticles. 32) Thus, we conclude that the vortex core states in Bi2212 are the bound states of Bogoliubov quasiparticles.…”

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confidence: 99%

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High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi₂Sr₂CaCu₂O_x

et al. 2013

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We studied electronic states in vortex cores of slightly overdoped Bi 2 Sr 2 CaCu 2 O x by scanning tunneling spectroscopy. We have found that they have stripe structures with a 4a 0 width extending along the Cu-O bond directions. Vortex core states are observed as two peaks at particle-hole symmetric positions in the energy gap. Along a stripe, the peak positions of vortex core states are constant and not influenced by the spatial variation of the energy gap Á. Outer stripes have a larger energy than inner stripes. A mazelike pattern in the electronic states at E ¼ AEÁ has been observed all over the surface both inside and outside the vortex core. The orientation of stripes of vortex core states was found to be related to the mazelike pattern in the vortex core region. A short-range order of the mazelike pattern spatially coexists with the superconductivity and locally breaks the symmetry of the two Cu-O bond directions. We propose that the vortex core bound states are formed by Bogoliubov quasiparticles owing to the depairing of Cooper pairs and have a local C 2 symmetry influenced by the short-range order of the mazelike pattern.KEYWORDS: Bi2212, high-T c superconductivity, vortex core, inhomogeneity, STM, STSIn vortex cores of type-II superconductors, the superconducting order parameter (pair potential) is suppressed in amplitude. Bogoliubov quasiparticles are confined in the vortex core to form Andreev bound states, reflecting the symmetry of the superconducting order parameter and the shape of the Fermi surface. Such vortex core bound states have been observed in the conventional s-wave superconductors NbSe 2 , 1) YNi 2 B 2 C, 2,3) and NbS 2 , 4) and recently in iron pnictides, 5-7) by scanning tunneling spectroscopy (STS). In d-wave superconductors, theoretical calculations based on the Bardeen-Cooper-Schrieffer theory predict that the vortex core bound states have a fourfold star-shaped spatial distribution extending in the nodal directions with a zero-bias conductance peak at the center of the vortex core. 8-10) However, STS experiments on the high-T c cuprate superconductor Bi 2 Sr 2 CaCu 2 O x (Bi2212) showed that the vortex core has characteristic states (vortex core states) at finite excitation energies E ¼ AE", and different values of " ranging from 7 to 16 meV have been reported by different research groups. 11-13) Vortex core states exhibit spatial modulations in the two Cu-O bond directions (anti-nodal directions) with a period of about 4a 0 , where a 0 is the Cu-O-Cu bond length (0.38 nm). 14,15) Our recent study has shown that the modulation of the electron-like state and that of the hole-like state are in antiphase with each other, and detected that the modulations are commensurate (4a 0 ) in one Cu-O bond direction and incommensurate (4:3a 0 ) in the other direction. 16) The latter means that the vortex core states locally have the C 2 symmetry instead of the C 4 symmetry of the CuO 2 unit cell. Many theoretical models [17][18][19][20][21][22][23][24][25][26][27][28] have been proposed to ex...

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“…[1][2][3][4] In the present case of Bi2212, tunneling spectra near the center of a vortex core still exhibit a clear energy gap, as can be seen in the spectrum at position Fig. 1( j)].…”

supporting

confidence: 51%

mentioning

confidence: 99%

High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi₂Sr₂CaCu₂O_x

et al. 2013

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“…This shift of the main peak originates from the Hall term. Similar shifts have been obtained by STS measurements 16,17 . Another check of validity can be done by examining the spatial dependence of the pair-potential and the circular current density near the vortex center.…”

Section: Equilibrium Casesupporting

confidence: 87%

DC Conductivity in an $$s$$ s -Wave Superconducting Single Vortex System

Arahata

Kato

2013

J Low Temp Phys

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DC conductivity in an s-wave superconducting single vortex system Keywords superconductivity, vortex, quasiclassical theory, impurity effect, self-consistent Born approximation, flux flow conductivity Abstract We study dynamics of a two-dimensional s-wave superconductor in the presence of a moving single vortex. Our analysis is based on the quasiclassical theory including the Hall term, generalized by Kita[T. Kita, PRB, 64, 054503 (2001)]. We numerically calculate the linear response of a moving single vortex driven by a dc external current in a self-consistent way, in the sense that Dyson equation, gap equation, Maxwell equations and generalized quasiclassical equation are solved simultaneously. We obtain Hall conductivity induced by vortex motion using the generalized quasiclassical equation, while we confirm that it vanishes in the conventional quasiclassical equation.

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“…By contrast, the tunneling spectrum at the center of one of the vortex core (Q) is nearly flat, reflecting the complete suppression of superconductivity in the core. The spectrum does not show a quasiparticle bound-state peak typical of vortex cores in clean-limit superconductors [11][12][13][14][15][16]. This suggest that our sample is in the dirty limit in the sense that the coherence length ξ is limited by the electron mean free path.…”

Section: Resultsmentioning

confidence: 98%

Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In

Yoshizawa

Kim

Kawakami

et al. 2015

e-J. Surf. Sci. Nanotech.

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We performed low-temperature scanning tunneling microscopy and spectroscopy on Si(111)-( √ 7× √ 3)-In in magnetic fields. Superconducting vortices were observed by mapping zero-bias conductance in an area consisting of flat terraces separated by atomic steps. While vortices in the terrace regions have an isotropic shape with a normal-state core, those at the atomic steps have anisotropic shapes and the superconductivity is only weakly suppressed in the cores. These properties are understood as a crossover from a normal vortex to a Josephson vortex. We conclude that the atomic steps work as Josephson junctions limiting the density of supercurrents.

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Quantum Limiting Behaviors of a Vortex Core in an Anisotropic Gap Superconductor

Cited by 35 publications

References 20 publications

High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi₂Sr₂CaCu₂O_x

High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi₂Sr₂CaCu₂O_x

DC Conductivity in an $$s$$ s -Wave Superconducting Single Vortex System

Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In

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Quantum Limiting Behaviors of a Vortex Core in an Anisotropic Gap Superconductor

Cited by 35 publications

References 20 publications

High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi2Sr2CaCu2Ox

High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi2Sr2CaCu2Ox

DC Conductivity in an $$s$$ s -Wave Superconducting Single Vortex System

Impact of Surface Conditions on the Superconductivity of Si(111)-(&radic;7 &times; &radic;3)-In

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Product

Resources

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High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi₂Sr₂CaCu₂O_x

High-Resolution Scanning Tunneling Spectroscopy of Vortex Cores in Inhomogeneous Electronic States of Bi₂Sr₂CaCu₂O_x

Impact of Surface Conditions on the Superconductivity of Si(111)-(√7 × √3)-In