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BCS superfluidity in the 2D Fermi-Hubbard model NSF, Simons Foundation, AFOSR MURI, NNSFC, CAS, NKBRSFC ICTP, Oct.28, 2014.

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Presentation on theme: "BCS superfluidity in the 2D Fermi-Hubbard model NSF, Simons Foundation, AFOSR MURI, NNSFC, CAS, NKBRSFC ICTP, Oct.28, 2014."— Presentation transcript:

1 BCS superfluidity in the 2D Fermi-Hubbard model NSF, Simons Foundation, AFOSR MURI, NNSFC, CAS, NKBRSFC ICTP, Oct.28, 2014

2 Youjin Deng, USTC Evgeny Kozik, King’s College Boris Svistunov Umass, Amherst arXiv:

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4 T-independent in Fermi-liquid

5 What do we know with meaningful error bars MOTT, AFM FM Stripes? AFM ? ? ? ? ? ? ?

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7 Cooper instability in the BCS regime Fermi-liquid form at determines is temperature (and frequency) independent in the limit

8 Protocol: Compute Fermi surface parameters ; verify their T-independence Transform Solve for eigenvectors and eigenfunctions Predicted divergence To determine compute correction (future work): is -independent, to leading order in small g

9 up to

10 p-pairing dominates only d-pairing

11 Finite n: and expansion to  Missed the phase for

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13 Dyson Equations: G&T-matrix self-consistent skeleton formulation ( contact potential ) BOLD DIAGRAMMATIC CALCULATION: Define “bare” pair propagator : ( exact solution of the two-body problem ) Skeleton diagrams In terms of “exact” or “fully dressed” propagators &

14 Compensation trick: Identical representation (under integration) Original representation Arbitrary auxiliary function with “Design” it to compensate

15 G&T-matrix self-consistent formulation ( contact potential ) BOLD DIAGRAMMATIC CALCULATION:

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18 p-d xy for U>4 T C for U<4 and n<0.7 Any dispersion relation for the same U and n For U>4.and. n>0.7 we need a different scheme SIMONS COLLABORATION ON MANY ELECTRON PROBLEM Conclusions/perspectives Zanchi, Schulz, PRB 61, (2000) d x2-y2 -AFM for U<2

19 High-order (at least order-6) calculations based on fully-dressed propagators should become a norm! Only self-consistent diagrams


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