2. Fermi surface, pseudogap and superconductivity in the t-J model
A. Ramšak and P. Prelovšek
Faculty of Mathematics and Physics (Univ. of Ljubljana)
J. Stefan Institute, Ljubljana, Slovenia
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3. t-J model

4. t-J Hamiltonian:
Green’s functions:
Spectral functions:

5. doping-dependent hopping
equations of
motion
for

6. doping-dependent hopping
equation of
motion
for
‘Self Consistent Born Approximation’:
; …..

7. doping-dependent hopping
equation of
motion
for
SCBA
decoupling

8. doping-dependent hopping
equation of
motion
for
SCBA
dynamical spin susceptibility

9. SCBA q
(0,)
(, )
(0,0)
(,0)

10. (0,)
(, )
(0,0)
(,0)

11. (0,)
(, )
(0,0)
(,0)

12. Fermi surface Exact diag.: large Fermi surface
One hole results: small Fermi surface
(hole pockets)

16. SCBA: 1 hole
Fermi arcs?

18. t’> 0
t’< 0

19. Finite doping
P. Prelovšek and A. Ramšak, Phys. Rev. B, 63, (R) (2001)

20. PG
P. Prelovšek and A. Ramšak, Phys. Rev. B, 63, (R) (2001)

21. A - B C ? D
Hole concentration versus chemical potential and the corresponding electron momentum distribution function nk.
P. Prelovšek and A. Ramšak (2002).

22. (A) ch=0.28 nk |nk| (0, ) (, ) (0, ) (, ) (0,0) (,0) (0,0)

23. (B) ch=0.19 nk |nk| (0, ) (, ) (0, ) (, ) (0,0) (,0) (0,0)

24. (C) ch=0.11 nk |nk| (0, ) (, ) (0, ) (, ) (0,0) (,0) (0,0)

25. (D) ch=0.04 nk |nk| (0, ) (, ) (0, ) (, ) (0,0) (,0) (0,0)

26. Aproximate analysis
(0,)
(, )
(0,0)
(,0)

27. (0, )
(0, 0)
(, )
(,0)

28. (0, )
(, )
(0,0)
(,0)

29. (0, )
(, )
(0,0)
(,0)

30. (0, )
(, )
(0,0)
(,0)

31. (0, )
(, )
(0,0)
(,0)

32. Pseudogap

33. A. Ramšak, P. Prelovšek, and I. Sega (2001)

34. QP
P. Prelovšek and A. Ramšak (2002).

35. A(k,) k kF
/t

38. Opening of the gap:

39. Temperature dependence:

40. Superconductivity
extract
Ramšak and Prelovšek, 2003

43. Summary
Fermi surface
Pseudogap
Superconductivity