Abstract
Superconducting condensation energy has been determined by integrating the electronic entropy in various iron pnictide/chalcogenide superconducting systems. It is found that with –4, which is in sharp contrast to the simple BCS prediction , with the quasiparticle density of states at the Fermi energy and the superconducting gap. A similar correlation holds if we compute the condensation energy through , with the effective normal state electronic specific heat coefficient. This indicates a general relationship with –2, which is not predicted by the BCS scheme. A picture based on quantum criticality is proposed to explain this phenomenon.
- Received 17 February 2014
- Revised 31 March 2014
DOI:https://doi.org/10.1103/PhysRevB.89.140503
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