Confirmation of anomalous superconductivity in subnano-scale particles

用扫描超导量子干涉仪(SQUID)研究了YBaCuO超导纳米粒子的局域磁性。在3K下获得的SSM图像清晰地显示了磁信号。纳米粒子内部不太可能形成量子化的通量，因为纳米粒子的大小等于YBaCuO的相干长度。事实上，SSM观测到的磁通量与量子化的磁通量是不同的。因此，观察到的磁信号被认为是来自亚纳米粒子组装内部的磁通量，这些亚纳米粒子通过约瑟夫森结相互连接。磁信号消失在体相T_c以下。

Local magnetic properties of YBaCuO superconducting nanoparticles were investigated by scanning Superconducting QUntum Interference Devise (SQUID) microscopy, SSM. The SSM image obtained at 3 K clearly showed magnetic signals. It is unlikely that quantized flux was formed inside a nanoparticle, because the size of nanoparticles is equivalent to the coherence length of YBaCuO. Indeed, the amount of magnetic flux observed by SSM was different from that of quantized flux. Thus, the observed magnetic signal is thought to originate from magnetic flux trapped inside the assembly of subnano-particles, which are connected with each other through Josephson junctions. The magnetic signal disappeared below bulk Tc.