Study of fluctuation conductivity in YBa2Cu3O7–δ films in strong magnetic fields


Вивчення флуктуаційної провідності в плівках YBa2Cu3O7–δ в сильних магнітних полях
Petrenko E.V. Omelchenko L.V. Kolesnichenko Yu.A. Shytov N.V. Rogacki K. Sergeyev D.M. Solovjov A.L.
December 2021B.Verkin Institute for Low Temperature Physics and Engineering of the NAS of Ukraine

Fizika Nizkikh Temperatur
2021#47Issue 121148 - 1156 pp.

We report the effect of the ab-plane magnetic field B up to 8 T on the resistivity ρ(T) and fluctuation conductivity σT) in YBa2Cu3O7–δ thin films. As expected, up to ~ 2.5 T the magnetic field monotonously increases ρ, the width of the resistive transition, ΔTc, and coherence length along the c axis, ξс(0), but decreases both Tc and the range of superconducting (SC) fluctuations ΔТfl. The fluctuation conductivity exhibits a crossover at characteristic temperature T0 from the 3D Aslamasov–Larkin (AL) theory near Tc to the 2D fluctuation theory of Maki–Thompson (MT). However, at B = 3 T, the MT term is completely suppressed, and above T0 (T) is unexpectedly described by the fluctuation contribution of 2D AL, suggesting the formation of a 2D vortex lattice in the film under the action of a magnetic field. At the same time, ΔТfl sharply increases by a factor of about 7, and ξс(0) demonstrates a very unusual dependence on Tc when B increases above 3 T. Our results demonstrate the possibility of the formation of a vortex state in YBCO and its evolution with increasing B.

Coherence length , Excess conductivity , Fluctuation conductivity , High-temperature superconductors , Magnetic field , YBCO films

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B. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, Kharkiv, 61103, Ukraine
Institute for Low Temperatures and Structure Research, Polish Academy of Sciences, Wroclaw, 50-950, Poland
K. Zhubanov Aktobe Regional State University, Aktobe, 030000, Kazakhstan
Faculty of Physics, V. N. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine

B. Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine
Institute for Low Temperatures and Structure Research
K. Zhubanov Aktobe Regional State University
Faculty of Physics

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