Kramer–Pesch Effect in Chiral <i>p</i>-Wave Superconductors

Kato, Yasuyuki; Hayashi, Nobuhiko

doi:10.1143/jpsj.70.3368

Cited by 31 publications

(47 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From panels (a) and (c) one can see that the Kramer-Pesch shrinking is rather sensitive to the surface roughness. This fully agrees with the usual expectations that the Kramer-Pesch effect in bulk s-wave superconductors is smeared out in the presence of impurities [23,24]. In contrast, the anomalous expansion of the vortex core is significantly more stable.…”

Section: Resultssupporting

confidence: 91%

Vortex anomaly in low-dimensional fermionic condensates: Quantum confinement breaks chirality

2014

View full text Add to dashboard Cite

Chiral fermions are responsible for low-temperature properties of vortices in fermionic condensates, both superconducting (charged) and superfluid (neutral). One of the most striking consequences of this fact is that the core of a single-quantum vortex collapses at low temperatures, T → 0 (i.e., the Kramer-Pesch effect for superconductors), due to the presence of chiral quasiparticles in the vortex-core region. We show that the situation changes drastically for fermionic condensates confined in quasi-one-dimensional and quasi-two-dimensional geometries. Here quantum confinement breaks the chirality of in-core fermions. As a result, instead of the ultimate shrinking, the core of a single-quantum vortex extends at low temperatures, and the condensate profile surprisingly mimics the multiquantum vortex behavior. Our findings are relevant for nanoscale superconductors, such as recent metallic nanoislands on silicon, and also for ultracold superfluid Fermi gases in cigar-shaped and pancake-shaped atomic traps.

show abstract

Section: Resultssupporting

confidence: 91%

Vortex anomaly in low-dimensional fermionic condensates: Quantum confinement breaks chirality

2014

View full text Add to dashboard Cite

show abstract

“…In a clean single-band superconductor, the order parameter exhibits the Kramer-Pesch ͑KP͒ effect, 49 i.e., shrinkage of the vortex core as T is lowered, approaching zero in the zero-temperature limit. 50,[69][70][71] In an s-wave superconductor, however, the core size as defined above saturates as temperature approaches zero, when there are nonmagnetic impurities. 50,71 This can be understood by the broadening of the vortex core bound states that carry the supercurrent around the vortex center.…”

Section: Temperature Dependencementioning

confidence: 99%

Theory of vortices in hybridized ballistic/diffusive-band superconductors

2007

View full text Add to dashboard Cite

We study the electronic structure in the vicinity of a vortex in a two-band superconductor in which the quasiparticle motion is ballistic in one band and diffusive in the other. This study is based on a model appropriate for such a case, that we have introduced recently ͓Tanaka et al., Phys. Rev. B 73, 220501͑R͒ ͑2006͔͒. We argue that in the two-band superconductor MgB 2 , such a case is realized. Motivated by the experimental findings on MgB 2 , we assume that superconductivity in the diffusive band is "weak," i.e., mostly induced. We examine intriguing features of the order parameter, the current density, and the vortex core spectrum in the "strong" ballistic band under the influence of hybridization with the "weak" diffusive band. Although the order parameter in the diffusive band is induced, the characteristic length scales in the two bands differ due to Coulomb interactions. The current density in the vortex core is dominated by the contribution from the ballistic band, while outside the core the contribution from the diffusive band can be substantial, or even dominating. The current density in the diffusive band has strong temperature dependence, exhibiting the Kramer-Pesch effect when hybridization is strong. A particularly interesting feature of our model is the possibility of additional bound states near the gap edge in the ballistic band, that are prominent in the vortex center spectra. This contrasts with the single band case, where there is no gap-edge bound state in the vortex center. We find the above-mentioned unique features for parameter values relevant for MgB 2 .

show abstract

“…The absence of impurity effects in vortex cores has another implication; the absence of impurity effects makes the Kramer-Pesch effect much more accessible in experiments of chiral p-wave superconductors than any other superconductors. 20) This can be, in principle, examined experimentally, e.g. by Muon spin relaxation measurements.…”

Section: Chiral P-wave Vortices Withmentioning

confidence: 99%

Numerical Study of Impurity Effects on Quasiparticles within S-wave and Chiral P-wave Vortices

Kato

Hayashi²

2002

J. Phys. Soc. Jpn.

Self Cite

View full text Add to dashboard Cite

The impurity problems within vortex cores of two-dimensional s-wave and chiral p-wave superconductors are studied numerically in the framework of the quasiclassical theory of superconductivity and self-consistent Born approximation under a trial form of the pair potential. The dispersion and impurity scattering rate (the inverse of the relaxation time) of the Andreev bound state localized in vortex cores are deduced from the angular-resoloved local density of states. The energy dependence of the impurity scattering rates depends on the pairing symmetry; particularly, in the chiral p-wave vortex core where chirality and vorticity have opposite sign and hence the total angular momentum is zero, the impurities are ineffective and the scattering rate is vanishingly small. Owing to the cancellation of angular momentum between chirality and vorticity, the chiral p-wave vortex core is similar to locally realized s-wave region and therefore non-magnetic impurity is harmless as a consequence of Anderson's theorem. The results of the present study confirm the previous results of analytical study (J. Phys. Soc. Jpn. 69 (2000) 3378) in the Born limit.KEYWORDS: superconductivity, vortex, quasiclassical theory, impurity effect, self-consistent Born approximation, chiral superconductor, flux flow conductivity §1. IntroductionVortex cores are often regarded as normal regions with the radius of the coherence length ξ 0 . This picture is valid only in the dirty superconductors where the mean free path l is much smaller than ξ 0 . In clean superconductors where l ≫ ξ 0 , quasiparticles experience the Andreev reflections 1) much often than collisions with impurities. The constructive interference at the multiple Andreev reflections leads to the Andreev bound states 2) in the cores; these states are nothing but the Caroli-deGennes-Matricon mode. 3)We could expect from the different character in quasiparticles that the flux flow conductivity σ f 4) is different between dirty and clean superconductors. This expectation is not fulfilled in isotropic s-wave superconductors; σ f in clean isotropic s-wave superconductors 5, 6) turns out to be different from that 7) in dirty superconductors only by a factor of ln (∆ ∞ /T ) at temperature T , where ∆ ∞ is the modulus of the pair-potential in the spatially uniform state.However, this is not the whole story. Volovik 8) pointed *

show abstract

Kramer–Pesch Effect in Chiral p-Wave Superconductors

Cited by 31 publications

References 33 publications

Vortex anomaly in low-dimensional fermionic condensates: Quantum confinement breaks chirality

Vortex anomaly in low-dimensional fermionic condensates: Quantum confinement breaks chirality

Theory of vortices in hybridized ballistic/diffusive-band superconductors

Numerical Study of Impurity Effects on Quasiparticles within S-wave and Chiral P-wave Vortices

Contact Info

Product

Resources

About