Effective Interaction in a Non-Fermi Liquid Conductor and Spin Correlations in Under-Doped Cuprates

Abstract

The effective interaction between the itinerant spin degrees of freedom in the paramagnetic phases of hole doped quantum Heisenberg antiferromagnets is investigated theoretically, based on the single-band t-J model on 1D lattice, at zero temperature. The effective spinspin interaction for this model in the strong correlation limit, is studied in terms of the generalized spin stiffness constant as a function of doping concentration. The plot of this generalized spin stiffness constant against doping shows a very high value of stiffness in the vicinity of zero doping and a very sharp fall with increase in doping concentration, signifying the rapid decay of original coupling of semi-localized spins in the system. Quite interestingly, this plot also shows a maximum occurring at a finite value of doping, which strongly suggests the tendency of the itinerant spins to couple again in the unconventional paramagnetic phase. As the doping is further increased, this new coupling is also suppressed and the spin response becomes analogous to almost Pauli-like. The last two predictions of ours are quite novel and may be directly tested by independent experiments and computational techniques in future. Our results in general receive good support from other theoretical works and experimental results extracted from the chains of YBa 2 Cu 3 O 6+x . arXiv:1705.05288v2 [cond-mat.str-el]

Local properties of the t-J model in a two-pole approximation within COM

“…This clearly shows that our solution correctly captures the behavior in this regime, consistently with the well-established AF Nï¿oeel state at half filling. The FM phase in the t-J model has been predicted in the literature [28,29,[33][34][35][36][37][38][39][40][41]: mobile holes can form Nagaoka polarons which results in a FM ordering [38,40]. We witness a similar behavior here, i.e., once enough holes are present in the system, FM correlations clearly emerge and they overcome the AF ones, whose correlation lengths decrease rapidly with doping [35].…”

“…Yet, Nagaoka proved that in the infinite-U regime of the Hubbard model, which corresponds to vanishing exchange integral in the t-J model, if we introduce one hole into the system the ground state becomes ferromagnetic (FM) [30][31][32]. This idea got generalized in the t-J model by so many successive studies which showed transition to FM phase for finite hole dopings [33][34][35][36][37][38][39][40][41].…”

Interplay of Pairing Correlation and Coulomb Correlation in Boson Exchange Superconductors

“…Then, we apply BCS pairing operator on the CFS states to form the correlated BCS(CBCS) states. The Gutzwiller partial projection operator is used to exclude the doubly occupied states for the HTSC antiferromagnetic cuprate superconducting system like, La 2−x Sr x CuO 4 , Y Ba 2 Cu 3 O 7 [22,23].…”