1. Where are the superconductors?
Z. Fisk, UC Irvine
Digital Synthesis Workshop
Boston University
September 27, 2013
Supported by AFOSR MURI

2. (from J. Schilling)

4. timeline of maximum superconducting transition temperature Tc

5. 1986: the new superconductors
La1.84Sr0.16CuO4 Tc = 40K

6. the new superconductors: pnictides Tc = 56K
Wolfgang Jeitschko
Hirano; 2008 Jorend

11. What is common here? all based on electron precise materials
charge separated layers
electronically anisotropic

12. competing order

13. M. Nicholas et al. Phys. Rev. B 76, 052401 (2007)

14. generic cuprate phase diagram

15. 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

17. Batterman and Barrett Phys. Rev. 145, 296 (1966)

18. Schilling V3Si: TMartensitic / Tc

19. 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

20. 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