Similarity of Slow Stripe Fluctuations between Sr-Doped Cuprates and Oxygen-Doped Nickelates

Jahn-Teller mechanism of stripe formation in doped layered La(2-x)Sr(x)NiO4 nickelates.

We introduce an effective model for e(g) electrons to describe quasi-two-dimensional layered La(2-x)Sr(x)NiO(4) nickelates and study it using correlated wavefunctions on 8 × 8 and 6 × 6 clusters. The effective Hamiltonian includes the kinetic energy, on-site Coulomb interactions for e(g) electrons (intraorbital U and Hund's exchange J(H)) and the coupling between e(g) electrons and Jahn-Teller ...

Nanoscopic stripe-like inhomogeneities and optical conductivity of doped cuprates

We propose a new approach to theoretical description of doped cuprate like La2−xSrxCuO4 and Y Ba2Cu3O6+x, assuming phase separation and treating it as inhomogeneous composite material, containing the dielectric and metallic stripelike nanoparticles. The formalism of effective medium theory is then applied for calculation of dielectric permittivity, optical and EELS spectra of La2−xSrxCuO4 with ...

Orbital ordering, new phases, and stripe formation in doped layered nickelates.

Ground-state properties of layered nickelates are investigated based on the orbital-degenerate Hubbard model coupled with lattice distortions, by using numerical techniques. The Néel state composed of spin S=1 ions is confirmed in the undoped limit x = 0. At x = 1/2, novel antiferromagnetic states, called CE- and E-type phases, are found by increasing the Hund's coupling. (3x2-r2/3y2-r2)-type o...

Electron Doped Cuprates

Competition between antiferromagnetism and superconductivity in the electron-doped cuprates triggered by oxygen reduction.

We have performed a systematic angle-resolved photoemission study of as-grown and oxygen-reduced Pr(2-x)CexCuO4 and Pr(1-x)LaCexCuO4 electron-doped cuprates. In contrast with the common belief, neither the band filling nor the band parameters are significantly affected by the oxygen reduction process. Instead, we show that the main electronic role of the reduction process is to remove an anisot...