Renormalization of quasiparticle hopping integrals by spin interactions in layered copper oxides

Abstract

Holes doped within the square CuO 2 network specific to the cuprate superconducting materials have oxygen 2p character. We investigate the basic properties of such oxygen holes by wave-function-based quantum chemical calculations on large embedded clusters. We find that a 2p hole induces ferromagnetic correlations among the nearest-neighbor Cu 3d spins. When moving through the antiferromagnetic background, the hole must bring along this spin-polarization cloud at nearby Cu sites, which gives rise to a substantial reduction of the effective hopping parameters. Such interactions can explain the relatively low values inferred for the effective hoppings by fitting the angle-resolved photoemission data. The effect of the background antiferromagnetic couplings of renormalizing the effective nearest-neighbor hopping is also confirmed by densitymatrix renormalization-group model-Hamiltonian calculations for chains and ladders of CuO 4 plaquettes.

Quasiparticle Bands in Cuprates by Quantum-Chemical Methods: Towards anAb InitioDescription of Strong Electron Correlations

“…That the charge populations of the Cu 3d and active O 2p orbitals are not sensitive to the size and shape of our clusters was shown in Ref. [15]. Apical ligands are explicitly included in our calculations only for the active plaquettes.…”

“…Renormalization effects on the nearest-neighbor (NN) effective hopping were previously investigated at the ab initio level in Ref. [15]. In this Letter, we show that accurate estimates for the longerrange hoppings are crucial for explaining both the dispersion observed by ARPES measurements and the FS in detail.…”

Fermiology of cuprates from first principles: From small pockets to the Luttinger Fermi surface

“…Such corrections are usually small, for both the on-site relative energies 22 and hoppings. 16,28 Nevertheless, corrections as large as 0.9 eV have been found before for the relative energy of the 1 A 1g state of the d 8 manifold in NiO, 22 for example. 29 The quantum chemical calculations allow an analysis of the strength of correlation effects in doped cuprates.…”

“…25,26 In contrast, the CASSCF calculations predict a renormalized NN hopping t = 0.135 eV in La 2 CuO 4 . 12,16 Here, we describe how the detailed QP dispersion can be obtained with quantitative accuracy, for both hole and electron-addition states. The effective hoppings are computed by using the overlap, S ij , and Hamiltonian, H ij , matrix elements between ͑N ϯ 1͒-particle wave functions having the additional particle ͑hole or electron͒ located on different plaquettes ͑i , j , ...͒ of a given cluster.…”

“…A similar scheme was previously applied to simpler, noncontroversial systems such as diamond, silicon, and MgO. [27][28][29] It accounts for both charge 27,28 and spin 12,16 polarization and relaxation effects in the nearby surroundings; see Fig. 1.…”