Spin polarised carrier injection into high T_c superconductor: A test for the superconductivity mechanism?

Abstract

We point out in this short communique, that be it a s-wave or d-wave superconductor, in a non equalibrium situation(i.e. in presence of excess unpolarised/polarised quasi-particles maintained by an injection current) the superconducting gap suppresion by the presence of same amount excess quasi-particles, can at best differ by a factor of 2, for a conventional BCS superconductor. For the high $T_c$ superconductors on the other hand, there is a huge difference in gap suppresion between upolarised/polarised quasiparticle injection, as observed in the experiments\cite{gold}. We argue that this this large anomaly has a natural explanation within the {\it Interleyer tunneling mechanism} of Wheatley, Hsu and Anderson\cite{and}, and is due to the excess polarised quasiparticles blocking the interlayer pair tunneling process. We also point out that spin polarised quasi-particle injection in a superconductor is a very easy way to distinguish between a s-wave or an anisotropic gap superconductor.