E. A. Stepanov, L. Peters, I. S. Krivenko, A. I. Lichtenstein, M. I. Katsnelson, A. N. Rubtsov
(Submitted on 13 Jun 2018)
Correlation effects in CuO2 layers give rise to a complicated landscape of collective excitations in high-Tc cuprates. Their description implies an accurate account for electronic fluctuations at a very broad energy range and remains a challenge for the theory. Particularly, there is no conventional explanation of the experimentally observed "resonant" antiferromagnetic mode, which is considered to be a mediator of superconductivity sometimes. Here we model spin excitations of the hole-doped La2CuO4 and show that this antiferromagnetic mode is associated with electronic transitions between van Hove singularities that are pinned to the Fermi level. Upon doping the reconstruction of the Fermi surface results in the flattening of the quasiparticle band at the vicinity of the (π/2,π/2) point, accompanied by the high density of charge carriers. Electronic spectral weight redistribution leads to formation of an additional magnetic holes state that, together with the unchanged quasiparticle dispersion, protects the antiferromagnetic fluctuation against changes with doping.