Anomalous Scaling Relations and Pairing Mechanism of the Fe-based Superconductors

International Conference on Strongly Correlated Electron Systems 2016

Bang, Yunkyu^1 ; Stewart, G.R.^2

Department of Physics, Chonnam National University, Kwangju

500-757, Korea, Republic of^1

Physics Department, University of Florida, Gainesville

FL

32611-8440, United States^2

关键词: Condensation energies;    Experimental evidence;    Kinematic constraints;    Pairing interactions;    Pairing mechanism;    Power law relation;    Repulsive interactions;    Superconducting compounds;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/807/5/052003/pdf
DOI  :  10.1088/1742-6596/807/5/052003

来源: IOP

【 摘 要 】

The anomalous scaling behavior of the specific heat jump ΔC vs. , first observed by Bud'ko et al[1], has been confirmed with several families of the Fe-based superconducting compounds with various dopings. And more recently, Xing et al[2] have reported that the condensation energy (CE) vs. Tcalso follows an anomalous power law with about forty different samples of the Fe-based superconductors. These apparently non-BCS power law relations have strongly hinted at a non-BCS pairing mechanism of the Fe-based superconductors. We have studied a minimal two band BCS model to understand these anomalous scaling behaviors and showed that these non-BCS relations of as well as can be well reproduced by the simple two-band BCS model paired by a dominant interband repulsive interaction (Vinter> Vintra> 0). The origin of these anomalous scaling relations are the kinematic constraint of near Tcof the two band BCS model, as realized in the S±-wave pairing state. Our results imply that these seemingly non-BCS-like scaling behaviors, on the contrary to the common expectations, are in fact strong experimental evidences that the pairing mechanism of the Fe-based superconductors is genuinely a BCS mechanism, meaning that the Cooper pairs are formed by the itinerant carriers glued by a pairing interaction.