Defects and an unusual superconductivity
Gor'kov L. P., Kalugin P. A.
If the superconducting gap in a pure material has zeros on an entire line along the Fermi surface, the state density is finite at e — 0, beginning with the lowest defect concentrations. The splitting of the superconducting transition by impurities, Uj _ x Thx Ben is discussed.