Doping dependence of the vortex-core energy in bilayer films of cuprates

Abstract

The energy needed to create a vortex core is the basic ingredient to address the physics of thermal vortex fluctuations in underdoped cuprates. Here, we theoretically investigate its role in the occurrence of the Beresinskii-Kosterlitz-Thouless transition in a bilayer film with inhomogeneity. From the comparison with recent measurements of the penetration depth in two-unit-cell thin films, we can extract the value of the vortex-core energy and show that scales linearly with T c at low doping.

Slowing down of vortex motion at the Berezinskii-Kosterlitz-Thouless transition in ultrathin NbN films

“…25,26 This leads to a drastic smearing of the superfluid-density jump predicted by the conventional BKT theory, in accordance with the experimental observations of the inductive response in thin films of conventional superconductors, 13,14 as measured by means of two-coil experiments. Notice that this experimental set-up measures the complex conductivity σ(ω) of a superconductor at low but finite frequency ω, usually ω 50 − 60 kHz.…”

Superconductor-insulator transition in disordered Josephson-junction chains

“…Phenomenologically, the correction (8) can be understood as follows 71,72 : the operator e 2iφ(x0,τ0) acts as a translation operator that shifts θ(x, τ ) after a time τ 0 and for x < x 0 by 2π, creating thus a QPS. A detailed microscopic derivation of Eq.…”

Vortex operator and BKT transition in Abelian duality

“…Furthermore, since the sine-Gordon description has been applied to investigate the BKT physics of quasi-two-dimensional superconductors [18], it is natural to expect that our new method based on path integral formulation of the Abelian duality and vortex operators may cast some lights on these problems [23]. On the other hand, the likewise Abelian duality may be developed for two dimensional field theories in a trap [23], thus our methods may be used to the theoretical analysis for recent ultracold-atom experiments on vortex physics of BKT transition [10]- [12][24]- [32], since these experiments are concentrated on interacting Bose gas in a two dimensional harmonic trap, in contrast to the infinite uniform system.…”

“…But the BKT transition can also be described by an effective field theory, the two-dimensional sine-Gordon model [14] [15]. The traditional derivations for this effective field theory description are via a complicated dual transformation in lattice theory [16] or through the Coulomb gas model [14][17] [18]. In this paper, we try to give a direct continuous field theoretic derivation, by further developing the path-integral formulation of the Abelian-duality of two dimensional quantum field theory [19].…”