Study of fluctuation conductivity in YBa2Cu3O7-δfilms in strong magnetic fields


Petrenko E.V. Omelchenko L.V. Kolesnichenko Yu.A. Shytov N.V. Rogacki K. Sergeyev D.M. Solovjov A.L.
1 December 2021American Institute of Physics Inc.

Low Temperature Physics
2021#47Issue 121050 - 1057 pp.

We report the effect of the ab-plane magnetic field B up to 8 T on the resistivity ρ(T) and fluctuation conductivity σ′(T) 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, ζC(0), but decreases both Tc and the range of superconducting (SC) fluctuations ΔTfl. 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 σ′(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, ΔTf sharply increases by a factor of about 7, and ζC(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.



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B. Verkin Institute for Low Temperature Physics and Engineering, 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
The Faculty of Physics, V. N. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine

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

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