D-wave bipolaronic condensate with short range repulsive electronic correlations in an extended hubbard model of high Tc cuprate superconductors

2001 ◽  
pp. 225-247 ◽  
Author(s):  
L.J. Dunne ◽  
E.J. Brändas
Keyword(s):  
Hubbard Model ◽  
Short Range ◽  
Cuprate Superconductors ◽  
Extended Hubbard Model ◽  
High Tc ◽  
Electronic Correlations ◽  
D Wave

scholarly journals INHOMOGENEOUS d-WAVE SUPERCONDUCTIVITY AND ANTIFERROMAGNETISM IN A TWO-DIMENSIONAL EXTENDED HUBBARD MODEL WITH NEAREST-NEIGHBOR ATTRACTIVE INTERACTION

2007 ◽  
Vol 21 (10) ◽  
pp. 573-584 ◽  
Author(s):  
W. P. SU
Keyword(s):  
Phase Separation ◽  
Hubbard Model ◽  
Cuprate Superconductors ◽  
Nearest Neighbor ◽  
Minimum Energy ◽  
Mean Field Approximation ◽  
Attractive Interaction ◽  
Two Dimensional ◽  
Extended Hubbard Model ◽  
D Wave

To understand the interplay of d-wave superconductivity and antiferromagnetism, we consider a two-dimensional extended Hubbard model with nearest neighbor attractive interaction. The Hamiltonian is solved in the mean field approximation on a finite lattice. In the impurity-free case, the minimum energy solutions show phase separation as predicted previously based on free energy argument. The phase separation tendency implies that the system can be easily rendered inhomogeneous by a small external perturbation. Explicit solutions of a model including weak impurity potentials are indeed inhomogeneous in the spin-density-wave and d-wave pairing order parameters. Relevance of the results to the inhomogeneous cuprate superconductors is discussed.

scholarly journals CRITICAL CURRENT IN THE HIGH-Tc GLASS MODEL

1999 ◽  
Vol 10 (07) ◽  
pp. 1335-1345
Author(s):  
I. MORGENSTERN ◽  
W. FETTES ◽  
T. HUSSLEIN
Keyword(s):  
Hubbard Model ◽  
Critical Current ◽  
Critical Currents ◽  
Microscopic Description ◽  
High Tc ◽  
Wave Pairing ◽  
Glass Model ◽  
Current Densities ◽  
D Wave

The high-Tc glass model can be combined with the repulsive tt'–Hubbard model as microscopic description of the striped domains found in the high-Tc materials. In this picture, the finite Hubbard clusters are the origin of the d-wave pairing. In this paper we show that the glass model can also explain the critical currents usually observed in the high-Tc materials. We use two different approaches to calculate the critical current densities of the high-Tc glass model. Both lead to a strongly anisotropic critical current. Finally we give an explanation of why we nonetheless expect a nearly perfect isotropic critical current in high-Tc superconductors.

scholarly journals Qualitative Picture of a New Mechanism for High-Tc Superconductors

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3284-3292
Author(s):  
Chia-Ren Hu
Keyword(s):  
Short Range ◽  
Coulomb Repulsion ◽  
Tunneling Conductance ◽  
High Tc Superconductors ◽  
Nernst Effect ◽  
High Tc ◽  
Ferromagnetic Order ◽  
Wave Nature ◽  
Qualitative Picture ◽  
D Wave

Xu et al. observed enhanced Nernst effect and Iguchi et al. observed patched diamagnetism, both well above Tc in underdoped high-Tc superconductors (HTSCs). A new mechanism is proposed here, which seems to naturally explain, at least qualitatively, these observations, as well as the d-wave nature and continuity of pseudogap and pairing gap, the tunneling conductance above Tc, as well as T*(x), Tν(x), Tc(x), etc. This mechanism combines features of dynamic charged stripes, preformed pairs, and spin-bags: At appropriete doping levels, the doped holes (and perhaps also electrons) will promote the formation of anti-phase islands in short-range anti-ferromagnetic order. On the boundary of each such island reside two doped carriers; the unscreened Coulomb repulsion between them stabilizes the island's size. Superconductivity results when such "pre-formed pairs" Bose-condense.

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