Electronic structure and magnetic properties of the spin-1/2 Heisenberg magnet Bi2CuO4

The electronic and magnetic structure of the spin-1/2 magnet Bi2CuO4 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 LSDA+U method for different spin configurations in magnetic supercells. Using our estimated exchange constants, we calculated the spin wave dispersion and the Neel temperature within the random phase approximation. The calculated properties are in good agreement with experimental data, suggesting that the magnetic ground state of Bi2CuO4 is governed by the antiferromagnetic interaction between the structural one-dimensional cuprate chains.