Koren Gad, Eyal Anna, Iomin Leonid, Nitzav Yuval
Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel.
Materials (Basel). 2021 Dec 13;14(24):7689. doi: 10.3390/ma14247689.
Nickelate films have recently attracted broad attention due to the observation of superconductivity in the infinite layer phase of Nd0.8Sr0.2NiO2 (obtained by reducing Sr doped NdNiO3 films) and their similarity to the cuprates high temperature superconductors. Here, we report on the observation of a new type of transport in oxygen poor Nd0.8Sr0.2NiO3-δ films. At high temperatures, variable range hopping is observed while at low temperatures a novel tunneling behavior is found where a Josephson-like tunneling junction characteristic with serial resistance is revealed. We attribute this phenomenon to coupling between superconductive (S) surfaces of the grains in our Oxygen poor films via the insulating (I) grain boundaries, which yields SIS junctions in series with the normal (N) resistance of the grains themselves. The similarity of the observed conductance spectra to the tunneling junction characteristic with Josephson-like current is striking, and seems to support the existence of superconductivity in our samples.
由于在Nd0.8Sr0.2NiO2的无限层相中观察到超导性（通过还原掺锶的NdNiO3薄膜获得）以及它们与铜酸盐高温超导体的相似性，镍酸盐薄膜最近引起了广泛关注。在此，我们报告了在贫氧的Nd0.8Sr0.2NiO3-δ薄膜中观察到的一种新型输运现象。在高温下，观察到变程跳跃，而在低温下发现了一种新颖的隧穿行为，其中揭示了具有串联电阻的类约瑟夫森隧穿结特性。我们将这种现象归因于贫氧薄膜中晶粒的超导（S）表面通过绝缘（I）晶界的耦合，这产生了与晶粒自身的正常（N）电阻串联的SIS结。观察到的电导谱与具有类约瑟夫森电流的隧穿结特性的相似性非常显著，似乎支持了我们样品中存在超导性。
