Flux pinning evolution in multilayer Pb/Ge/Pb/Ge/Pb superconducting systems

Abstract

Multicomponent superconductors exhibit nontrivial vortex behaviors due to the various vortex-vortex interactions, including the competing one in the recently proposed type-1.5 superconductor. However, potential candidate that can be used to study the multicomponent superconductivity is rare. Here, we prepared an artificial superconducting multilayer to act as an alternative approach to study multicomponent superconductivity. The additional repulsive length and the coupling strength among superconducting films were regulated by changing the thickness of the insulting layer. The magnetization measurements were performed to clarify the effect of the competition between the repulsive vortex interactions on the macroscopic superconductivity. The vortex phase diagram and the optimum critical current density have been determined. Furthermore, a second magnetization effect is observed, and is attributed to the upper layer, which provides the weak pinning sites to localize the flux lines. The pinning behaviors switches to the mixed type with the increase of the insulting layer thicknesses. Our results open a new perspective to the study and related applications of the multilayer superconducting systems.

Role of grain boundary networks in vortex motion in superconducting films

“…Pinning plays a crucial role in determining the vortex dynamics in the mixed state of type-II superconductors, which is important for lossless transport in the applications of superconductors. [1][2][3][4][5][6][7][8][9] It has been suggested to introduce many defects as effective pinning centers against the driving force of magnetic flux flow. Of them, twin boundaries may be the most significant anisotropic pinning defects in the cuprate compound YBa 2 Cu 3 O 7−x (YBCO).…”