Seminarium Fizyki Materii Skondensowanej

We study the evolution of the spectral properties upon hole or electron doping the Mott insulating state [1]. The spectral function of the Hubbard and t-J-like models is calculated using the cluster perturbation theory. We find that the features associated with the spin polaron and the 3-site terms dispersion, which dominate the Mott insulating spectrum [2], persist up to ca. 25% (40%) hole (electron) doping. We identify a quasi-free dispersion relation which crosses the Fermi level, develops at an almost infinitesimally small hole or electron doping, and evolves to a dispersion relation that is almost indistinguishable from the one given by the tight-binding model at the high doping level. Although naively such a quasi-free dispersion seems to be closely related to the free electronic hopping, our main result is that both the electron-electron correlations as well as the spin exchange interactions inherently influence this spectral feature. An intuitive explanation of this phenomenon is discussed and it is suggested that the “pseudogaps” can easily occur in such doped Mott insulators.[1] Y. Wang et al., unpublished (2017).[2] Y. Wang et al., Phys. Rev. B 92, 075119 (2015).