1 / 31

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.

ghada
Download Presentation

Opening…

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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…

More Related