Periodic flux jump in superconducting Pb networks as consequence of the extended Little-Parks effect

Ishida, Takekazu*; Matsushima, Yoshiaki*; Shimizu, Makoto*; Hayashi, Masahiko*; Ebisawa, Hiromichi*; Sato, Osamu*; Kato, Masaru*; Koyama, Tomio*; Machida, Masahiko  ; Sato, Kazuo*; Yotsuya, Tsutomu*

The extended Little-Parks effect of superconducting network is known as a periodic variation as a function of magnetic field. Superconducting Pb honeycomb networks of matching field 0.106 G and triangular microhole lattice of Pb of matching field 0.425 G have been fabricated by the combination of electron-beam lithography and a lift-off process of evaporated Pb films. The application of magnetic field corresponds to the vortex filling into superconducting networks. We measured the magnetization of the networks systematically by using a SQUID magnetometer. We found that flux jump appears rather periodically as a function of magnetic field. Flux jumps may be induced by a periodic decrease of the critical current density of the network. To the authors' knowledge, this is for the first time to observe the regular flux jumps due to the critical current modification coming from the extended Little-Parks effect of the superconducting networks.