In the Bi2Sr2CaCu2O8 + δ high-temperature superconductor system, which has a layered crystal structure and very large anisotropy, the superconducting layers are coupled by the Josephson effect and the crystal itself naturally makes a stack of Josephson tunnel junctions in series, called intrinsic Josephson junctions. Associated with such a layered strucure of the intrinsic Josephson junctions, heating due to current injection is significant. In order to observe their tunneling characteristics, it is necessary to fabricate very thin and small samples and thereby reduce the heating due to current injection. We have fabricated such very thin samples and observed tunneling characteristics of the intrinsic Josephson juncitons. The observed current-voltage characteristics and the gap voltage are very different from those of conventional superconductors. They can be explained in terms of the symmetry of the superconducting order parameter and the evolution of a pseudogap.
|ジャーナル||NTT R and D|
|出版物ステータス||Published - 1998 12 1|
ASJC Scopus subject areas
- Electrical and Electronic Engineering