Where are the superconductors?
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Transcript of Where are the superconductors?
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Where are the superconductors?
Z. Fisk, UC Irvine
Digital Synthesis Workshop
Boston University
September 27, 2013
Supported by AFOSR MURI
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(from J. Schilling)
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timeline of maximum superconducting transition temperature Tc
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1986: the new superconductors
La1.84Sr0.16CuO4 Tc = 40K
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the new superconductors: pnictides Tc = 56K
Wolfgang Jeitschko
2006 Hirano; 2008 Jorend
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What is common here?
• all based on electron precise materials
• charge separated layers
• electronically anisotropic
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competing order
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M. Nicholas et al. Phys. Rev. B 76, 052401 (2007)
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generic cuprate phase diagram
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BCS-type A15 superconductivity
• Peierls-type lattice distortion above Tc
• strong coupling of soft lattice mode to conduction electrons
• no lattice distortion when Tc occurs first
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Batterman and Barrett Phys. Rev. 145, 296 (1966)
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Schilling V3Si: TMartensitic / Tc
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highest Tc found in proximity to competing “localized” phase
• holds for BCS, heavy Fermions, organics, cuprates and pnictides
• the competing phase, afm in heavy Fermions, terminates where it intersects the Tcboundary and does not extend into the superconducting phase
• “localized”: in BCS, lattice distorted; in heavy Fermions, local moment magnetism; in cuprates, the psuedo-gap phase.
• electronics highly non-adiabatic
• superconductivity runs in structures
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• superconductivity appears as solution to unloading entropy of fluctuations
• gaps out lower frequency fluctuations
• It seems plausible that a connection between structure, character of fluctuations and superconductivity exists