科研之友
微信
新浪微博
Facebook
分享链接
摘要
Based on the ab initio band structure for NaxCoO2, we derive the single-electron energies and the effective tight-binding description for the t(2g) bands using projection procedure. Due to the presence of the next-nearest-neighbor hoppings, a local minimum in the electronic dispersion close to the Gamma point of the first Brillouin zone forms. Correspondingly, in addition to a large Fermi surface, an electron pocket close to the Gamma point emerges at high doping concentrations. The latter yields a scattering channel, resulting in a peak structure of the itinerant magnetic susceptibility at small momenta. This indicates dominant itinerant in-plane ferromagnetic fluctuations above a certain critical concentration x(m), in agreement with neutron scattering data. Below x(m), the magnetic susceptibility shows a tendency toward the antiferromagnetic fluctuations. We further analyze the many-body effects on the electronic and magnetic excitations using various approximations applicable for different U/t ratios.
- 出版日期2007-3
