Study of effective coupling between charge degrees of freedom in low dimensional hole-doped quantum antiferromagnets

Abstract

Expressions for generalized charge stiffness constant at zero temperature are derived corresponding to low dimensional hole doped quantum antiferromagnets, describable by the t-J-like models, with a view to understanding fermionic pairing possibilities and charge couplings in the itinerant antiferromagnetic systems. A detailed comparison between spin and charge correlations and couplings are presented in both strong and weak coupling limits. The result highlights that the charge and spin couplings show very similar behaviour in the over-doped region in both the dimensions, whereas they show a completely different trend in the lower doping regimes. A qualitative equivalence of generalized charge stiffness constant with the effective Drude weight and Coulomb interaction is established based on the comparison with other theoretical and experimental results. The fall in charge stiffness with increase in doping then implies reduction in the magnitude of effective Coulomb repulsion between the mobile carriers. This leads to an enhanced possibility of fermionic pairing with increase in doping in the possible presence of some other attraction producing mechanism from a source outside the t-J-like models. Moreover, under certain conditions in the optimal doping region, the t-J-like models themselves are able to produce attractive interaction for pairing.

Some aspects of Microscopic Mechanism of Superconductivity in conventional and non-conventional systems

“…The above equation shows the possibility of V ef f turning attractive for ω → 0, in the RPA-like treatment of correlated phase [18]. Our results bring out a clear possibility of the existence of attractive interaction between the mobile carries in the k−space in the optimally doped and over-doped regimes only.…”

“…The nature of the effective interaction between the itinerant carries in the Cu − O layers in this doped phase, decides the superconducting pairing possibility. Keeping this in mind, we had theoretically calculated the generalized charge stiffness constant for the t−J like models on 2D square lattice [18]. We scanned the entire doping regime from underdoped to over-doped.…”