R. Hayn

Spin-polaron damping in the spin-fermion model for cuprate superconductors

A self-consistent, spin rotational invariant Greens function procedure has been developed to calculate the spectral function of carrier excitations in the spin-fermion model for the CuO2 plane. We start from the mean field description of a spin polaron in the Mori-Zwanzig projection method. In order to determine the spin polaron lifetime in the self-consistent Born approximation, the self-energy is expressed by an irreducible Greens function. Both, spin polaron and bare hole spectral functions are calculated. The numerical results show a well pronounced quasiparticle peak near the bottom of the dispersion at (pi/2,pi/2), the absence of the quasiparticle at the Gamma-point, a rather large damping away from the minimum and an asymmetry of the spectral function with respect to the antiferromagnetic Brillouin zone. These findings are in qualitative agreement with photoemission data for undoped cuprates. The direct oxygen-oxygen hopping is responsible for a more isotropic minimum at (pi/2,pi/2).

ANISOTROPIC SUPEREXCHANGE OF A 90 CU-O-CU BOND

The magnetic anisotropy of a rectangular Cu-O-Cu bond is investigated in second order of the spin-orbit interaction. Such a bond is characteristic for cuprates having edge sharing CuO2 chains, and exists also in the Cu3O4 plane or in ladder compounds. For a ferromagnetic coupling between the copper spins an easy axis is found perpendicular to the copper oxygen plaquettes in agreement with the experimental spin structure of Li2CuO2. In addition, a pseudodipolar interaction is derived. Its estimation in the case of the Cu3O4 plane (which is present for instance in Ba2Cu3O4Cl2 or Sr2Cu3O4Cl2) gives a value which is, however, two orders of magnitude smaller than the usual dipole-dipole interaction.

Analysis of the valence-band photoemission spectrum of Sr2CuO2Cl2 along the high-symmetry directions

Band structure calculations have been used to identify the different bands contributing to the polarization-dependent photoemission spectra of the undoped model cuprate

Effective equations for disordered one-dimensional systems

{\mathrm{Sr}}_{2}{\mathrm{CuO}}_{2}{\mathrm{Cl}}_{2}

Non-rigid hole band in the extended t-J model

at the high-symmetry points of the

Transport through a band insulator with Rashba spin-orbit coupling: metal-insulator transition and spin-filtering effects

{\mathrm{CuO}}_{2}

On the Peierls transition in the presence of disorder

plane

Exchange integrals and magnetization distribution in BaCu2X2O7 (X=Ge,Si)

\ensuremath{\Gamma},

Tight-binding parameters and exchange integrals of Ba 2 Cu 3 O 4 Cl 2

(\ensuremath{\pi}/a,0)