Temperature Dependent Gap Anisotropy from Interlayer Tunneling

Abstract

A recent experiment by Ma and collaborators shows that the gap anisotropy in ${\rm Bi}_2 {\rm Sr}_2 {\rm Ca}_1 {\rm Cu}_2 {\rm O}_{8+x}$ is strongly temperature dependent. In particular, the superconducting gap along the $Γ- M$ direction shows a weaker temperature dependence than the gap along the $Γ- X$ direction which decreases rapidly with temperature. We explain this novel feature as a natural consequence of the interlayer tunneling mechanism of superconductivity.