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arXiv · 1412.1034

Quantum Criticality in the 122 Iron Pnictide Superconductors Emerging from Orbital-Selective Mottness

S. D. Das·M. S. Laad·L. Craco·J. Gillett·V. Tripathi·S. E. Sebastian
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Abstract

The twin issues of the nature of the normal state and competing order(s) in the iron arsenides are central to understanding their unconventional, high-Tc superconductivity. We use a combination of transport anisotropy measurements on detwinned Sr(Fe(1-x)Co(x))2As2 single crystals and local density approximation plus dynamical mean field theory (LDA + DMFT) calculations to revisit these issues. The peculiar resistivity anisotropy and its evolution with x are naturally interpreted in terms of an underlying orbital-selective Mott transition (OSMT) that gaps out the dxz or dyz states. Further, we use a Landau-Ginzburg approach using LDA + DMFT input to rationalize a wide range of anomalies seen up to optimal doping, providing strong evidence for secondary electronic nematic order. These findings suggest that strong dynamical fluctuations linked to a marginal quantum-critical point associated with this OSMT and a secondary electronic nematic order constitute an intrinsically electronic pairing mechanism for superconductivity in Fe arsenides.

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S. D. Das, M. S. Laad, L. Craco, J. Gillett, V. Tripathi, S. E. Sebastian. 2015-10-14. Quantum Criticality in the 122 Iron Pnictide Superconductors Emerging from Orbital-Selective Mottness. https://doi.org/10.1103/physrevb.92.155112

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