Prof. Vladimir Kogan (Iowa State University and Ames Laboratory DOE)
Following the seminal work of Abrikosov and Gor'kov on the pair-breaking effects, one can derive the temperature dependences of the electronic specific heat in the superconducting state, the London penetration depth , and the slope of the upper critical field near the critical temperature for materials with zero Fermi surface average of the order parameter (e.g. d-wave) or for those with this average being small (e.g., ±s of iron-pnictides) in the presence of strong pair-breaking. A remarkably simple relation between these at first sight unrelated quantities can be derived. The prediction is checked on two samples of Ba(Fe_(1−x)Co_x)_2As_2 and on CeCoIn_5 for which the data needed are available