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Title: Complex conductance of ultrathin La 2-xSr xCuO 4 films and heterostructures

We used atomic-layer molecular beam epitaxy to synthesize bilayers of a cuprate metal (La 1.55Sr 0.45CuO 4) and a cuprate insulator (La 2CuO 4), in which each layer is just one unit cells thick. We have studied the magnetic field and temperature dependence of the complex sheet conductance, σ(ω), of these films. Experiments have been carried out at frequencies between 2 and 50 MHz using the single-spiral coil technique. We found that: (i) the inductive response starts at ΔT = 3 K lower temperatures than Re σ(T), which in turn is characterized by a peak close to the transition, (ii) this shift is almost constant with magnetic field up to 14 mT; (iii) ΔT increases sharply up to 4 K at larger fields and becomes constant up to 8 T; (iv) the vortexdiffusion constant D(T) is not linear with T at low temperatures as in the case of free vortices, but is rather exponential due to pinning of vortex cores, and (v) the dynamic Berezinski–Kosterlitz–Thouless (BKT) transition temperature occurs at the point where Y=(l ω/ξ+) 2 = 1. As a result, our experimental results can be described well by the extended dynamic theory of the BKT transition and dynamics ofmore » bound vortex–antivortex pairs with short separation lengths.« less
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  1. Brookhaven National Lab. (BNL), Upton, NY (United States); Yale Univ., New Haven, CT (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1063-777X; LTPHEG; R&D Project: MA509MACA; KC0203020
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Low Temperature Physics
Additional Journal Information:
Journal Volume: 41; Journal Issue: 12; Journal ID: ISSN 1063-777X
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; superconducting heterostructures; high-frequency conductivity; Berezinski-Kosterlitz-Thouless transition; rotating flows; coils; inductance; magnetic fields; metallic thin films
OSTI Identifier: