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Fermion Glue in the Hubbard Model: New Insights into the Cuprate Pairing Mechanism with Advanced Computing

This paper discusses new insights into the cuprate pairing mechanism in high-temperature superconductors using advanced computing. It explores the Fermion Glue theory in the Hubbard model and the role of strong electronic correlations in superconductivity.

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Fermion Glue in the Hubbard Model: New Insights into the Cuprate Pairing Mechanism with Advanced Computing

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  1. Fermion Glue in the Hubbard Model:New Insights into the Cuprate Pairing Mechanism with Advanced Computing Thomas C. Schulthess Computer Science and Mathematics Division Center for Nanophase Materials Sciences

  2. t U t Outline Superconductivity A model for high-temperaturesuperconductors Non-super-conductive metal Resistance Superconductor Tc Temperature 0 K Algorithm andleadership computing 50 New scientific insights 40 3/2m 30 20 Vd 10 1/2d 0 -10 irr U = 8t; No = 4;(n) = 0.85 -20 -30 T/t 0.0 0.5 1.0 1.5 2.0 2.5 3.0

  3. LHe Power requirementsfor cooling versus temperaturein Kelvin LH2 LNe LN2 0 20 40 60 80 100 What is superconductivity? • A macroscopic quantum state with • Zero resistance • Perfect diamagnetism • Applications: • MAGLEV, MRI,power transmission, generators, motors • Only disadvantage: • Cooling necessary • Tc ≈ 150 K in HTSC • Ultimate goal: • Tc ≈ room temperature Non-super-conductive metal Resistance Superconductor Tc Temperature 0 K

  4. Discovered byBednorz and Müllerin 1986 High-temperature superconductors HgTlBaCuO 1995 140 HgBaCaCuO 1993 High temperaturenon-BCS TIBaCaCuO 1988 BiSrCaCuO 1980 100 YBa2Cu3O7 19870 Liquid H2 T [K] 60 Low temperature BCS La2-xBaxCuO4 1986 MgB2 2001 NbC Nb=A1=Ge 20 Pb V3Si Nb3Ge Nb3Su LiquidHe NbN Hg Bednorzand Müller Nb 1940 1920 1960 1980 2000 • Highly anisotropic • SuperconductingCuO - planes BCS Theory

  5. t U t 2D Hubbard model ofhigh-temperature superconductors HTSC: 1023interacting electrons DCA/QMC:Map Hubbard model onto embedded cluster 2D Hubbard modelfor CuO planes

  6. ➙ dger or delay updating ➙ dgemm Algorithm and leadership computing: Fixed startup cost favors fewer,faster processors ➙ Cray X1E (N = 4480) (4480 x 32) Measurement ➙ cgemm G Sample QMC time Warm up G G G Warm up Warm up Warm up

  7. - + + - Superconductivity as a consequence of strong electronic correlations (TAM et al., PRL ‘05)

  8. - + + - Pairing interaction:A matter of perspective Pairing interaction = + + Γph Γpp Λirr Γph Γ Γ Mechanism (Pfitzner and Wölfle, PRB 1989; Esirgen and Bickers, PRB 1998) Calulate with DCA/QMC (Maier et al., PRL 2006) Fully irreducible S = 0 S = 1

  9. - + + - 50 U = 8t; No = 4; (n) = 0.85 3/2m 40 Vd 1/2d 30 Spin irr 20 Pairing 10 Fully irr. 0 -10 Charge -20 -30 0.0 0.5 1.0 1.5 2.0 2.5 3.0 T/t Magnetic origin of pairing interaction • Attractive pairing interaction between nearest neighbor singlets • Dynamicsassociated with antiferromagnetic spin fluctuation spectrum • Pairing interaction mediated by antiferromagnetic fluctuations Maier et al., PRL 2006 Maier et al., PRB 2006 Maier et al., in preparation

  10. Summary/Conclusions/Outlook • Superconductivity: A macroscopic quantum effect • 2D Hubbard model for strongly correlatedhigh-temperature superconducting cuprates • Dynamic cluster quantum Monte Carlo simulationson Cray X1E • Superconductivity as a result of strong correlations • Pairing mediated by antiferromagnetic spin fluctuations • Simple spin susceptibility representationof pairing interaction? • Verification by neutron scattering experiments?

  11. Contacts Thomas Maier Oak Ridge National Laboratory (865) 576-3597 maierta@ornl.gov Paul Kent Oak Ridge National Laboratory (865) 574-4845 kentpr@ornl.gov Thomas Schulthess Oak Ridge National Laboratory (865) 574-4344 schulthesstc@ornl.gov 11 Schulthess_Superconductivity_0611

  12. The Team University of California University of Cincinnati Oak RidgeNational Lab D. Scalapino M. Jarrell Paul Kent Thomas Maier Thomas Schulthess

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