[13p-B408-1~16] 11.1 Fundamental properties

△ [13p-B408-16] The electric transport properties of NdFeAs(O,H) epitaxial thin films

〇Keisuke Kondo¹, Motoki Seiya¹, Hatano Takafumi¹, Iida Kazumasa^1,2, Ikuta Hiroshi¹ (1.Nagoya Univ., 2.JST CREST)

Keywords:superconductor, iron-based superconducting thin film, hydrogen doping

We have successfully fabricated hydrogen doped epitaxial NdFeAsO thin films and investigated their electrical transport properties. X-ray analyses revealed that the NdFeAs(O,H) film grew phase-pure and epitaxially on MgO (001) with a cube-on-cube configuration. The film showed a high superconducting transition temperature T_c of 49 K. Compared with a NdFeAs(O,F) film having similar T_c, the carrier density n of the NdFeAs(O,H) film was lager: n for NdFeAs(O,H) was around 5×10²¹ cm^-3 at 50 K, whereas the corresponding value for NdFeAs(O,F) was around 2×10²¹ cm^-3. The upper critical field for H || c of NdFeAs(O,H) was almost comparable to that of NdFeAs(O,F), but, NdFeAs(O,H) showed a wider irreversible region. This may be due to the increase in the interlayer coupling, which was similarly observed in cuprates with over-doping. The self-field critical current density J_c was in excess of 17 MA/cm² at 4 K, which corresponds to 13% of the depairing current density of NdFeAs(O,F).