Vortex-induced strain and magnetization in type-II superconductors

Kogan, V. G.

doi:10.1103/physrevb.87.020503

Cited by 12 publications

(3 citation statements)

References 19 publications

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“…Recently, it has been shown that stress induced intervortex interaction can lead to square vortex lattice in tetragonal superconductors 38 . Such a coupling between crystalline elasticity and superconductivity can be treated using the dependence of T c with pressure, dT c /dP 36,[39][40][41] . Generally, with dT c /dP > 0, vortices are repelled from places with internal stress and the opposite occurs with dT c /dP < 0.…”

Section: Discussionmentioning

confidence: 99%

Observation of a gel of quantum vortices in a superconductor at very low magnetic fields

Llorens

Embon

Correa

et al. 2020

Phys. Rev. Research

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A gel consists of a network of particles or molecules formed for example using the sol-gel process, by which a solution transforms into a porous solid. Particles or molecules in a gel are mainly organized on a scaffold that makes up a porous system. Quantized vortices in type II superconductors mostly form spatially homogeneous ordered or amorphous solids. Here we present high-resolution imaging of the vortex lattice displaying dense vortex clusters separated by sparse or entirely vortex-free regions in β-Bi2Pd superconductor. We find that the intervortex distance diverges upon decreasing the magnetic field and that vortex lattice images follow a multifractal behavior. These properties, characteristic of gels, establish the presence of a novel vortex distribution, distinctly different from the well-studied disordered and glassy phases observed in high-temperature and conventional superconductors. The observed behavior is caused by a scaffold of one-dimensional structural defects with enhanced stress close to the defects. The vortex gel might often occur in type-II superconductors at low magnetic fields. Such vortex distributions should allow to considerably simplify control over vortex positions and manipulation of quantum vortex states. arXiv:1904.10999v2 [cond-mat.supr-con]

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Section: Discussionmentioning

confidence: 99%

Observation of a gel of quantum vortices in a superconductor at very low magnetic fields

Llorens

Embon

Correa

et al. 2020

Phys. Rev. Research

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“…According to Kogan et al . 17 the strains in this type of composite system arise due to the difference in density of the normal (i.e. InBi) and superconducting (i.e.…”

Section: Resultsmentioning

confidence: 99%

Routes to probe Bismuth induced strong-coupling superconductivity in bimetallic BiIn alloys

Gandhi

2017

Sci Rep

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We report the observation of strong electron-phonon coupling in intergranular linked BiIn superconductors over an infinite range mediated by low-lying phonons. An enhanced superconducting transition temperature was observed from the magnetization, revealing a main diamagnetic Meissner state below T C (0) = 5.86(1) K and a critical field H C (0) = 1355(15) Oe with an In 2 Bi phase of the composite sample. The electron-phonon coupling to low lying phonons is found to be the leading mechanism for observed strong-coupling superconductivity in the BiIn system. Our findings suggest that In 2 Bi is in the strong-coupling region with T C (0) = 5.62(1) K, λ ep = 1.45, ω ln = 45.92 K and α = 2.23. The estimated upper critical field can be well-described by a power law with α value higher than 2, consistent with the strong electron-phonon coupling.Recently a number of electron-phonon coupled bi-and tri-metallic superconductors with enhanced superconducting transition have been discovered, renewing interest in conventional phonon-mediated superconductivity 1-4 . We consider the BiIn bimetallic system, in which Bi is a semimetal and In is a weak-coupled superconductor with transition temperature T C (0) = 3.4 K (at ambient atmosphere). When annealed together they form In 2 Bi, In 5 Bi 3 and InBi bimetallic compounds and a solid solution, α-In 5 . The reported T C (0) for single crystals of In 2 Bi and In 5 Bi 3 are 5.1 K and 4.1 K, respectively, whereas InBi is a non-superconductor down to 0.5 K. Hutcherson et al. 6 reported the two-gap superconductivity in a composite (In 2 Bi + In 5 Bi 3 ) superconductor with T C1 (0) = 5.6 K and T C2 (0) = 4.1 K. A microscopic examination of polished InBi samples revealed a heterogeneous mixture of crystal grains, except for pure crystalline phases indicating granular superconductivity. In such a system, the Josephson tunneling between superconducting grains establishes inter-granular links and results in macroscopic superconductivity 7 . However, a comprehensive study, including electron-phonon coupling strength and the enhanced T C in the InBi system, has not yet been carried out. Conventionally, BCS-Eliashberg theory showed that T C is the combined effect of electron-phonon coupling strength (λ ep ) and phonon energy (ω ln ). In this study, we present a transition of weak to strong electron-coupling superconductivity by tuning the Bi concentration in bimetallic Bi y In 1-y alloys, consisting of two superconducting gaps at y = 0.1, 0.2, 0.6, and 0.7 and a single gap at y = 0.01, 0.2, 0.3, 0.4 and 0.5, respectively. The enhancement of T C (0) = 5.62(1) K was observed at y = 0.3, led by low lying phonons that can be well described by using Allen and Dynes' theory 2 . ResultsCrystal structure analysis of BiIn alloy. Figure 1(a) presents the typical EDS spectra, showing a series of elemental Bi and In constituents that can be assigned to Bi-Ma 1 , In-Lα 1 , In-Lβ 1 , and In-Lβ 2 , respectively. The small peaks of C and Cu were the result of the carbon film on the Cu grid from mounting ...

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“…A vortex can perturb the strain field of the crystal that induces additional interactions between vortices [12][13][14][15][16][17]. In a simple picture, nucleation of the normal vortex core which has a different density than the surrounding superconductor, induces a strain field.…”

Section: Introductionmentioning

confidence: 99%

Strain-induced intervortex interaction and vortex lattices in tetragonal superconductors

Lin

Kogan

2017

Phys. Rev. B

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In superconductors with strong coupling between superconductivity and elasticity manifested in a strong dependence of transition temperature on pressure, there is an additional contribution to inter-vortex interactions due to the strain field generated by vortices. When vortex lines are along the c axis of a tetragonal crystal, a square vortex lattice (VL) is favored at low vortex densities, because the vortex-induced strains contribution to the inter-vortex interactions is long range. At intermediate magnetic fields, the triangular lattice is stabilized. The triangular lattice evolves to the square lattice upon increasing magnetic field, and eventually the system locks to the square structure. We argue, however, that as magnetic field approaches the upper critical field H c2 the elastic inter-vortex interactions disappear faster than the standard London interactions, so that VL should return to the triangular structure. Our results are compared to VLs observed in the heavy fermion superconductor CeCoIn 5 .

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Vortex-induced strain and magnetization in type-II superconductors

Cited by 12 publications

References 19 publications

Observation of a gel of quantum vortices in a superconductor at very low magnetic fields

Observation of a gel of quantum vortices in a superconductor at very low magnetic fields

Routes to probe Bismuth induced strong-coupling superconductivity in bimetallic BiIn alloys

Strain-induced intervortex interaction and vortex lattices in tetragonal superconductors

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