Negligible oxygen vacancies, low critical current density, electric‐field modulation, in‐plane anisotropic and high‐field transport of a superconducting Nd <sub>0.8</sub> Sr <sub>0.2</sub> NiO <sub>2</sub> /SrTiO <sub>3</sub> heterostructure
Xiaorong Zhou, Zexin Feng, Peixin Qin, Han Yan, Xiaoning Wang, Pan Nie, Haojiang Wu, Xin Zhang, Hongyu Chen, Ziang Meng, Zengwei Zhu, Zhiqi Liu
Abstract
Abstract The emerging Ni‐based superconducting oxide thin films are rather intriguing to the entire condensed matter physics. Here, we report some brief experimental results on transport measurements for a 14‐nm‐thick superconducting Nd 0.8 Sr 0.2 NiO 2 /SrTiO 3 thin‐film heterostructure with an onset transition temperature of ~ 9.5 K. Photoluminescence measurements reveal that there is negligible oxygen vacancy creation in the SrTiO 3 substrate during thin‐film deposition and post chemical reduction for the Nd 0.8 Sr 0.2 NiO 2 /SrTiO 3 heterostructure. It was found that the critical current density of the Nd 0.8 Sr 0.2 NiO 2 /SrTiO 3 thin‐film heterostructure is relatively small, ~ 4 × 10 3 A·cm −2 . Although the surface steps of SrTiO 3 substrates lead to an anisotropy for in‐plane resistivity, the superconducting transition temperatures are almost the same. The out‐of‐plane magnetotransport measurements yield an upper critical field of ~ 11.4 T and an estimated in‐plane Ginzburg–Landau coherence length of ~ 5.4 nm. High‐field magnetotransport measurements up to 50 T reveal anisotropic critical fields at 1.8 K for three different measurement geometries and a complicated Hall effect. An electric field applied via the SrTiO 3 substrate slightly varies the superconducting transition temperature. These experimental results could be useful for this rapidly developing field.