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Opening…

Opening…. A DFT (LDA+U) Study of the Electronic Properties of Layered, Square-Planar Coordinated Copper Monoxide Structures -- Proxies for High Temperature Superconductivity --. Paul M. Grant IBM Research Staff Member, Emeritus. Financial Support From: IBM Retiree Pension Fund Prior to 1990.

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  1. Opening…

  2. A DFT (LDA+U) Study of the Electronic Properties of Layered, Square-Planar Coordinated Copper Monoxide Structures-- Proxies for High Temperature Superconductivity -- Paul M. GrantIBM Research Staff Member, Emeritus Financial Support From: IBM Retiree Pension Fund Prior to 1990 Aging IBM Pensioner

  3. Prelude “Electronic Properties of Rocksalt Copper Monoxide,” APS MAR09-2008-006217, P. M. Grant, Pittsburgh (2009)

  4. Tools • QUANTUM-ESPRESSO Suit of Codes • DFT (LDA+U) plus electron-phonon • Graphics by Tone Kolalj (XCrysDen) • www.quantum-espresso.org • “Dial-in” Parameters • G2 = 40 Ryρ = 320 Ry • Convergence ≤ 10-6Ry • “Smearing” = Methfessel-Paxton • Psuedopotentials: Ultrasoft, XC = Perdew-ZungerCu: 3d94s2 O: 2s22p4 • Hardware • 3.33 GHz Intel Core i7 – 12 GB+

  5. Findings Basic Asymmetric af-CuO Cell Spin Up

  6. Are TherePhonons w/ High-Tc in YBCO? Fig. 38: Pintschovius and Reichardt, in Furrer, ISBN 0-7923-5226-2

  7. Yes -- They’re There! Pyka, et al., PRL 70, 1457, (1993) Harashima, et al., Physica C263, 257 (1996)

  8. Macfarlane, Rosen, Seki, SSC 63, 831 (1987) Raman Spectroscopy of YBCO

  9. Cu O Cubic Rocksalt Copper Monoxide a = b = c = 3.905 Å

  10. Rocksalt CuO Combined DOS N(E) (states/eV) EF = 16.74 eV eV

  11. Rocksalt CuO BZ X M Γ X X

  12. Rocksalt CuO Bands Note Degeneracies! eV EF X Γ X X M Γ X

  13. Rocksalt CuO Band Widths Note Degeneracies!

  14. Rocksalt CuO Fermiology 5 8 12 10

  15. Rocksalt CuO Fermiology (Combined) Note (Near) Degeneracies! Jahn-Teller Unstable? Alex M?

  16. Non-Magnetic Cubic Rocksalt CuO-- Electron-Phonon Properties -- α2F(ω) • λ ~ 0.6 – 0.7 • Other sc’s… σ = 0.04

  17. Square-Planar Copper Monoxide “Film” a = b = 3.905 Å c = 6 x 3.905 = 23.43 Å

  18. “Thin Film” Rocksalt CuO Combined DOS N(E) (states/eV) EF = -2.29 eV eV

  19. “Thin Film” CuO BZ X M Z Γ X

  20. “Thin Film” CuO Bands Note Degeneracies! eV EF Γ M X Γ Z X X

  21. “Thin Film” CuO Band Widths Note Band Offsets!

  22. “Thin Film” CuO Fermiology (Combined) 2kF • “Nesting Fermi Lines” • → CDW? → SDW? → HTSC? •  ~ ?

  23. “Rocks” “Films”

  24. “Rocks” “Films”

  25. “Rocks” “Films”

  26. “Rocks” “Films” “Jahn – Teller” “Nesting”

  27. af-CuO c=6*a U~0.001 eV

  28. af-CuO c=6*a U~0.001 eV

  29. af-CuO c=6*a U~0.001 eV

  30. Shakes & Spins Copacetic, Competitive or Conundrum? That is the question…anon • Bottom Line: • Can studying CuO proxies with DFT • + LDA+U • + phonons • provide the answer? • I say “Yes,” but… • How to compute λ(SDW)? • Size Matters… • …and I need a… BIGGER COMPUTER! 3D phase diagram of overdoped La2-xCexCuO4 with 0.15 ≤ x ≤ 0.19. Pairing associated with quantum critical energy scales in superconducting electron-doped cuprates K. Jin, N. P. Butch, K. Kirshenbaum, J. Paglione, and R. L. Greene* -submitted to Nature- *will answer all questions…

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