Pair-pair interactions in high-Tc superconductivity: Evidence from tunneling experiments


William Sacks

Sorbonne Universities, Paris


The conventional BCS theory fails to account for the physical properties of a large variety of high-Tc superconductors, the cuprate family and the recently discovered iron-based superconductors. In particular, these materials reveal a `peak-dip-hump' structure in the quasiparticle DOS at low temperature and often a pseudogap at the critical temperature.


In my talk, the origin of these features are explained in the framework of a new pair-pair interaction model [1]:


- The non-superconducting state consists of incoherent pairs, a `Cooper-pair glass' which, due to the pair-pair interaction, condense below Tc to the coherent superconducting state.


- The peak-dip-hump structure is then due to the strong coupling between quasiparticles and excited pairs, which we call `super-quasiparticles'.


The talk will focus on a wide variety of tunneling experiments, with varied temperature, magnetic field and doping, to test the validity of the model.


[1] W. Sacks, A. Mauger, Y. Noat, Superconduct. Sci. Technol. 28 105014, (2015)