Nakayama Akiyoshi, Abe Susumu, Watanabe Norimichi, Okabe Yoichi
Department of Engineering, Kanagawa University, Yokohama, 221-8686, Japan.
J Nanosci Nanotechnol. 2012 Jun;12(6):5016-20. doi: 10.1166/jnn.2012.4903.
Two-dimensional (2-D) magnetic field dependences of Niobium/niobium tunnel junction current Ic were first used in order to measure the magnetic field near the superconducting film. The 2-D magnetic field dependences of superconducting Josephson current Ic through the niobium/niobium tunnel junction can be changed by the external magnetic field. So, we measured the magnetic field using this superconducting tunnel junction fabricated by DC-magnetron apparatus as a magnetic sensor. The 2-D magnetic field dependences of Ic through the junction without and with the Nb thin-film sample were compared. With the Nb thin-film sample, extension of the characteristics in the perpendicular direction Hz to the sample was observed because of the Meissner effect of the superconducting thin-film sample. Moreover, the magnetic field Hz perpendicular to the Nb thin-film sample has been added in the triangle shape as a following sequence: (0)-(1000)-(0)-(2000)-(0)-(3000)-(0)-(4000)-(0)-(5000 A/m)-(0). Significant changes in the measured Ic-H (Hy,Hz) characteristics were observed above the certain value of Hz > 3000 A/m. We consider the shift of the measured Ic-H dependence in the Hz minus direction occurred because of the flux quanta were trapped in the sample superconducting niobium film after the Hz value had been added greater than 3000 A/m.
为了测量超导薄膜附近的磁场，首次使用了铌/铌隧道结电流Ic的二维（2-D）磁场依赖性。通过铌/铌隧道结的超导约瑟夫森电流Ic的二维磁场依赖性会因外部磁场而改变。因此，我们使用由直流磁控管设备制造的这种超导隧道结作为磁传感器来测量磁场。比较了在没有和有Nb薄膜样品的情况下通过结的Ic的二维磁场依赖性。对于Nb薄膜样品，由于超导薄膜样品的迈斯纳效应，观察到了在垂直于样品的Hz方向上特性的扩展。此外，垂直于Nb薄膜样品的磁场Hz以如下顺序呈三角形添加：(0)-(1000)-(0)-(2000)-(0)-(3000)-(0)-(4000)-(0)-(5000 A/m)-(0)。在Hz > 3000 A/m的特定值以上，观察到测量的Ic-H（Hy，Hz）特性有显著变化。我们认为，在Hz值添加大于3000 A/m之后，由于磁通量子被困在样品超导铌薄膜中，导致测量的Ic-H依赖性在Hz负方向上发生了偏移。
