https://doi.org/10.1140/epjb/e2020-10221-4
Regular Article
Spin and charge fluctuations in the two-band Hubbard model
Institute of Physics, University of Tartu,
1 W. Ostwaldi Street,
50411
Tartu, Estonia
a e-mail: alekseis@ut.ee
Received:
30
April
2020
Received in final form:
26
June
2020
Published online: 2 September 2020
A model of CuO2 planes of cuprate perovskites, containing dx2−y2 copper orbitals and symmetric combinations of oxygen pσ orbitals, is investigated using the strong coupling diagram technique. This approach allows one to take into account the interactions of carriers with spin and charge fluctuations of all ranges. Derived equations for Green’s function are self-consistently solved for the set of parameters corresponding to hole- and electron-doped cuprates. It is shown that the mentioned interactions lead to the appearance of spin polarons – bound states of carriers with spin excitations, which show themselves as sharp peaks of the density of states and spectral functions at the Fermi level. Hole and electron doping are strongly asymmetric. This, in particular, manifests itself in the antiferromagnetic response for the electron-doped case and in an incommensurate magnetic ordering for hole doping. In the latter case, the incommensurability parameter grows with doping. The double occupancy shows that the electron-doped system retains strong correlations up to the concentration 0.23, while for hole doping the correlations decay rapidly. These results are in agreement with experimental observations in cuprates.
Key words: Solid State and Materials
© EDP Sciences / Società Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020