Spatial structure of spin polarons in thet−Jmodel

Abstract

The deformation of the quantum Néel state induced by a spin polaron is analyzed in a slave fermion approach. Our method is based on the selfconsistent Born approximation for Green's and the wave function for the quasiparticle. The results of various spin-correlation functions relative to the position of the moving hole are discussed and shown to agree with those available from small cluster calculations. Antiferromagnetic correlations in the direct neighborhood of the hole are reduced, but they remain antiferromagnetic even for J as small as 0.1t . These correlation functions exhibit dipolar distortions in the spin structure, which sensitively depend on the momentum of the quasiparticle. Their asymptotic decay with the distance from the hole is governed by power laws, yet the spectral weight of the quasiparticles does not vanish.

Spin Polarons in Two-Dimensional Systems

“…The validity of the SCBA is further corroborated by a careful variational approach to a single-hole problem in the intermediate-coupling regime [20] (see also [21]). An interesting problem of the space structure of spin polarons was studied using the "exact", within SCBA, polaron wave function [22], see [23,24]. From the SCBA wave function [22] it is possible to prove that the spin polaron spectral weight is non-vanishing in the thermodynamic limit, contrary to an earlier criticism.…”

Reiter's Polaron Wave Function Applied to a t2gOrbital t-J Model

“…with three-site terms included) with those obtained for the spin Ising model and for the spin SU(2) symmetric model in Refs. [6,7]. On the one hand, for all n the dependence of the norm N (n) kL on k resembles to some extent the spin SU(2) model.…”

“…On the one hand, for all n the dependence of the norm N (n) kL on k resembles to some extent the spin SU(2) model. On the other hand, a closer look reveals that even for k = (0, 0) the dependence of N (n) kL on J is a concave function for all n just as for the spin Ising case and unlike in the SU(2) case where it can be a convex function of J for some n [7]. Hence, the detailed study of the Reiter's wave function of the orbital polaron confirms that the hole doped into the t 2g AO forms a mobile polaron just like the mobile spin polaron in the AF plane of high-T c cuprates [2] but its properties are truly distinct, in agreement with discussion in Ref.…”

Origin of band and localized electron states in photoemission of NiO

“…Physically this QP is different from a normal polaron; the hopping of the hole (ϳt) acts to increase locally the quantum spin fluctuations, melting the ''spin solid'' in its immediate neighborhood. The motion of the hole is accompanied by a backflow of spin fluid, 10 allowing it to move coherently throughout the lattice ͑''spin-liquid polaron''͒.…”

“…22 While the t-J model is a generic Hamiltonian, another and more realistic route may be followed by considering spin-fermion models that result from the full electronic structure in the strongly correlated regime, if both the symmetry of the doped holes and the multiplet structure of 3d states are taken into account. 10,23 If the Coulomb interactions are strong enough, it is in general possible to integrate out perturbatively the 3d charge degrees of freedom. The problem that remains is that of a carrier that is strongly coupled to the spin background.…”