Coherent versus incoherent c-axis Josephson tunneling between layered superconductors

We calculate Ic(T) and Rn for both coherent and incoherent electron tunneling across a c-axis break junction between two ν=s,dx2-y2-wave layered superconducting half spaces, each with c-axis bandwidth 2J. Coherent quasiparticle tunneling only occurs for voltages V<2J/e, leading to difficulties in measuring Rn for underdoped samples. The coherent part of Ic(0) is independent of Δν(0) for J/Δν(0)<1, and can be large. Our results are discussed with regard to recent experiments. copyright 1998 The American Physical Society