High J_c and low anisotropy of hydrogen doped NdFeAsO superconducting thin film.

ABSTRACT: The recent realisations of hydrogen doped LnFeAsO (Ln?=?Nd and Sm) superconducting epitaxial thin films call for further investigation of their structural and electrical transport properties. Here, we report on the microstructure of a NdFeAs(O,H) epitaxial thin film and its temperature, field, and orientation dependencies of the resistivity and the critical current density J_c. The superconducting transition temperature T_c is comparable to NdFeAs(O,F). Transmission electron microscopy investigation supported that hydrogen is homogenously substituted for oxygen. A high self-field J_c of over 10 MA/cm² was recorded at 5 K, which is likely to be caused by a short London penetration depth. The anisotropic Ginzburg-Landau scaling for the angle dependence of J_c yielded temperature-dependent scaling parameters ?_J that decreased from 1.6 at 30 K to 1.3 at 5 K. This is opposite to the behaviour of NdFeAs(O,F). Additionally, ?_J of NdFeAs(O,H) is smaller than that of NdFeAs(O,F). Our results indicate that heavily electron doping by means of hydrogen substitution for oxygen in LnFeAsO is highly beneficial for achieving high J_c with low anisotropy without compromising T_c, which is favourable for high-field magnet applications.

SUBMITTER: Iida K 

PROVIDER: S-EPMC7952916 | biostudies-literature | 2021 Mar

REPOSITORIES: biostudies-literature