Critical-field slope reduction and upward curvature of the phase-transition lines of thin disordered superconducting YBa2Cu3O7-x films in strong magnetic fields

Antonov, A.V.; Ikonnikov, A.V.; Masterov, D.V.; Mikhaylov, A.N.; Morozov, S.V.; Nozdrin, Y.N.; Pavlov, S.A.; Parafin, A.E.; Tetel’baum, D.I.; Ustavschikov, S.S.; Vasiliev, V.K.; Yunin, P.A.; Savinov, D.A.

Авторы: Antonov A.V., Ikonnikov A.V., Masterov D.V., Mikhaylov A.N., Morozov S.V., Nozdrin Yu N., Pavlov S.A., Parafin A.E., Tetel’baum D.I., Ustavschikov S.S., Vasiliev V.K., Yunin P.A., Savinov D.A.
Журнал: Physica C: Superconductivity and its Applications
Том: 568
Год издания: 2020
Издательство: Elsevier BV
Местоположение издательства: Netherlands
Номер статьи: 1353581
DOI: 10.1016/j.physc.2019.1353581
Аннотация: We report the effect of disorder on superconducting phase transition of epitaxial thin films in external magnetic fields. The disorder was produced by several successive acts of oxygen ion implantation. Controlling a total accumulated dose of implanted ions nD, we carried out transport measurements in ab-plane for temperatures T below 91 K and external magnetic fields H up to 11 T. Temperature-field dependencies of in-plane resistivity allow us to analyze phase diagrams for primary compound as well as for disordered structure. Considering the upper critical field Hc2 as the magnetic field which corresponds to a local resistivity drop at the onset of superconducting transition, we found out the following results. By gradual increasing of nD, the phase-transition line Hc2(T) suffers an unconventional critical-field slope reduction, while larger defect concentrations usually enhance the upper critical field in the vicinity of Tc0. Besides, for rather large nD, the curvature of Hc2(T) becomes upward for temperatures close to Tc0. Theoretical interpretation of the experimental data is developed in the framework of linearized Ginzburg-Landau theory with an inhomogeneous superconducting coherence length. A simple expression for the critical temperature Tc is obtained: where h is the dimensionless magnetic field and α is a constant which describes the defects in a specimen. The formula nicely fits our experimental results.
Добавил в систему: Иконников Антон Владимирович

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Critical-field slope reduction and upward curvature of the phase-transition lines of thin disordered superconducting YBa2Cu3O7-x films in strong magnetic fieldsстатья