Electronic structure and magnetic properties of the spin-1∕2Heisenberg magnetBi2CuO4

Abstract

The electronic and magnetic structure of the spin-$1∕2$ magnet ${\mathrm{Bi}}_{2}\mathrm{Cu}{\mathrm{O}}_{4}$ is investigated by band structure calculations within the local (spin) density approximation [L(S)DA]. The insulating compound shows a complex of narrow, half-filled antibonding bands within the LDA, indicating the importance of strong on-site correlation effects. To describe the lowest-lying excitations, the strong Coulomb correlations have been taken into account by a subsequent mapping of the LDA band structure onto a tight-binding model and via an extended Hubbard model onto an extended Heisenberg model. Alternatively, the leading exchange interactions have been estimated applying the $\mathrm{LSDA}+U$ method for different spin configurations in magnetic supercells. Using our estimated exchange constants, we calculated the spin wave dispersion and the N\'eel temperature within the random phase approximation. The calculated properties are in good agreement with experimental data, suggesting that the magnetic ground state of ${\mathrm{Bi}}_{2}\mathrm{Cu}{\mathrm{O}}_{4}$ is governed by the antiferromagnetic interaction between the structural one-dimensional cuprate chains.