Superconductivity (SC) is one of the most intriguing physical phenomena in nature. Nucleation of SC has long been considered highly unfavorable if not impossible near ferromagnetism, in low dimensionality and, above all, out of non-superconductor. Here we report observation of SC with TC near 4 K in Ni/Bi bilayers that defies all known paradigms of superconductivity, where neither ferromagnetic Ni film nor rhombohedra Bi film is superconducting in isolation. This highly unusual SC is independent of the growth order (Ni/Bi or Bi/Ni), but highly sensitive to the constituent layer thicknesses. Most importantly, the SC, distinctively non-s pairing, is triggered from, but does not occur at, the Bi/Ni interface. Using point contact Andreev reflection, we show evidences that the unique SC, naturally compatible with magnetism, is triplet p-wave pairing. This new revelation may lead to unconventional avenues to explore novel SC for applications in superconducting spintronics.
Epitaxial stabilization of an orthorhombic Mg-Ti-O superconductor
钛氧化物超导体具有许多与铜酸盐和铁磷属元素化物/硫属元素化物类似的有趣现象，为对比研究高温超导体的非常规配对机制提供了一个理想的平台。在这里，我们成功地沉积Mg-Ti-O超导薄膜MgAl $_2$ O $_4$基板上的三个主要取向通过烧蚀MgTi $_2$ O $_4$目标。特别地，令人惊讶地观察到，在（011）取向的衬底上生长了非预期结构的单晶膜，其中最高零电阻转变温度（$T_{\mathrm{c}0}$）为5.0 K。该薄膜具有高度降低的Mg/Ti比和正交晶系Ti $_9$ O $_{10}$样结构（表示为Mg：Ti $_9$ O $_{10}$），通过进一步的化学组成和结构表征证明。这样的结构在体中是不稳定的，但是由于在所形成的界面处的相对小的应变而有利于在MgAl $_2$ O $_4$的（011）表面上外延稳定。在Mg：Ti $_9$ O $_{10}$薄膜中观察到一个各向同性的上临界场（$B_{\mathrm{c}2}$），其最高可达13.7 T，突破了泡利极限，类似于其它超导钛氧化物。这种相似性表明了该族化合物超导电性的共同起源，这将为过渡金属化合物非常规超导电性的机理提供有价值的见解。
In situ Al$_2$O$_3$ passivation of epitaxial tantalum and aluminum films enables long-term stability in superconducting microwave resonators
Grad. Institute of Applied Physics and Dept. of Physics, National Taiwan University（国立台湾大学应用物理研究所及物理系）；Department of Physics, National Tsing Hua University（国立清华大学物理系）；National Synchrotron Radiation Research Center（国家同步辐射研究中心）；Taiwan Semiconductor Research Institute（台湾半导体研究院）
