Apical oxygens and correlation strength in electron- and hole-doped copper oxides

Abstract

We use the Local Density Approximation in combination with the Dynamical Mean Field Theory to carry out a comparative investigation of a typical electron doped and a typical hole doped copper oxide, NCCO and LSCO respectively. The parent compounds of both materials are strongly correlated electron systems in the vicinity of the metal to charge transfer insulator transition. In NCCO the magnetic long range order is essential to open a charge transfer gap, while Mott physics is responsible for the gap in LSCO. We highlights the role of the apical oxygens in determining the strength of the correlations and obtaining overall good agreement between theory and several experimentally determined quantities. Results for optical conductivity, polarized X-ray absorption and angle resolved photoemission are presented and compared with experiments.

DMFT Study on the Electron–hole Asymmetry of the Electron Correlation Strength in the High Tc Cuprates

“…The difference in the d-p offset and hence the on-site U rises because the electron-doped cuprates, with the T'-type structure, have no apical oxygen, while La 2 CuO 4 having the T-type structure has apical oxygens at close distance to the copper atom. [16][17][18][19] However, a recent first principles estimation 20) has revealed that La 2 CuO 4 is actually an exception that has very large d-p level offset, while many of the hole-doped cuprates have d-p offset values and hence the on-site U comparable to those in the T'-type electron doped systems. A typical example with a moderate d-p offset and U is HgBa 2 CuO 4 , in which T c is very high (∼ 100K) and a pseudo gap is observed.…”

Eliashberg analysis of the optical conductivity in superconducting Pr2CuOxwithx≃ 4

“…Superconductivity reported in undoped cuprates challenges the applicability of the CTI picture to electron-doped cuprates [16]. It is worth noting here that recent calculations performed on the basis of a new first-principles method report a sharp difference between the parent compounds with T and T ′ structures [17,18,19]. While the first are found to be "standard" CTIs, the latter, e.g.…”

Ultrafast dynamics in the presence of antiferromagnetic correlations in electron-doped cuprate La2−xCexCuO4±δ

“…Dynamical mean-field theory (DMFT) calculations have indicated that around 10% electron doping, the primary optical excitations permissible with a 1.5 eV pump are from the quasiparticle band into the upper Hubbard band [26]. Additional but less probable possibilities exist for excitation from the low-energy tail of the Zhang-Rice singlet band (centered at −2.1 eV in Ref.…”

“…Additional but less probable possibilities exist for excitation from the low-energy tail of the Zhang-Rice singlet band (centered at −2.1 eV in Ref. [26]) into the quasiparticle band. The quasiparticle band is implicated in both superconductivity and AF, and at this doping, its momentum-integrated electronic DOS is split into two peaks separated by 2 AF on either side of the Fermi level E F .…”