Pseudogaps and magnetic properties of the two-dimensional t-J model

TL;DR

This study uses a modified spin-wave theory to analyze the pseudogap and magnetic properties of the 2D t-J model, revealing non-metallic behavior, Fermi surface changes, and agreement with experimental data in underdoped cuprates.

Contribution

It introduces a self-consistent approach to study the pseudogap phenomena and magnetic properties in the 2D t-J model, aligning theoretical results with experimental observations.

Findings

Identification of pseudogap opening near (pi,0) with decreasing doping

Violation of Luttinger's theorem in the hole spectrum

Qualitative and quantitative agreement with experimental data in cuprates

Abstract

We apply the modified spin-wave theory with the constraint of zero staggered magnetization to investigate normal-state spectral and magnetic properties of the 2D t-J model in the paramagnetic state. A set of self-energy equations for hole and magnon Green's functions is solved numerically in the self-consistent Born approximation. The constraint can be fulfilled in the ranges of hole concentrations 0.02 < x < 0.17 and temperatures T < 150 K. In this region the hole spectrum differs from a conventional metallic spectrum which is manifested in the variation with x of the quasiparticle weights of states and in the violation of Luttinger's theorem. With decreasing x from x = 0.17 hidden parts appear in the hole Fermi surface which can be interpreted as the opening of a pseudogap near (pi,0). Obtained size, symmetry and concentration dependence of the pseudogap are in agreement with photoemission data in Bi2212. Calculated temperature dependencies of the spin correlation length, spin-lattice relaxation times at the Cu and O sites, and static susceptibility are typical for the quantum disordered regime with a pseudogap in the spectrum of magnetic excitations. These quantities are in qualitative and in some cases in quantitative agreement with experiment in underdoped YBa2Cu3O(6+y). At x > 0.12 the considered phase borders the phase of conventional metal.