Images of Interlayer Josephson Vortices in Tl 2 Ba 2 CuO 6+ δ

Abstract

The strength of the interlayer Josephson tunneling in layered superconductors is an essential test of the interlayer tunneling model as a mechanism for superconductivity, as well as a useful phenomenological parameter. A scanning superconducting quantum interference device (SQUID) microscope was used to image interlayer Josephson vortices in Tl 2 Ba 2 CuO 6+ δ and to obtain a direct measure of the interlayer tunneling in a high–transition temperature superconductor with a single copper oxide plane per unit cell. The measured interlayer penetration depth, λ c , is ∼20 micrometers, about 20 times the penetration depth required by the interlayer tunneling model.