Please have a look on these papers:

J. Phys. Soc. Jpn. 86, 044710 (2017)

Phys. Rev. B 92, 134505 (2015)

dear Prof. Dinesh Kumar Dixit

You may find interesting the following paper by Prof. Peter Hirschfeld [1]. He discuss reasons for competition between pairing in s- and d-wave channels & gives some examples of s anisotropic gaps for a particular system of Fe-based superconductors.

On the other hand, an isotropic gap has only a constant value Delta = Delta0. Notice please that, isotropic or anisotropic s-wave gaps do not have zeros (don´t touch the Fermi surface)

[1]

Article Using Gap Symmetry and Structure to Reveal the Pairing Mecha...