We consider the covalence characters of the 3d electron with the eg orbital freedoms and put forward a new mechanism of the orbital ordering （00） based on the direct coulomb repulsion in this article. The results sh...We consider the covalence characters of the 3d electron with the eg orbital freedoms and put forward a new mechanism of the orbital ordering （00） based on the direct coulomb repulsion in this article. The results show that the orbital-orbital interaction （OO-I） between the adjacent ions in 180-degree configuration is dominated by the superexchange energy accompanied by a weak orbital-spin coupling, and the OO-I in 90-degree configuration is monitored by the oxygen on-site coulomb repulsion. The ferro-OO is the stable ground state for the one-dimensional chain in the case of the 90-degree configuration.展开更多
In the present paper, we investigate the existence of ferromagnetism in a two-band Hubbard model, by applying a recently-introduced method by us to study ferromagnetism in metallic dusters. We prove rigorously that th...In the present paper, we investigate the existence of ferromagnetism in a two-band Hubbard model, by applying a recently-introduced method by us to study ferromagnetism in metallic dusters. We prove rigorously that the ground state of this model is ferromagnetic if the intra-orbital Coulomb repulsion between electrons is infinitely strong and only one hole exists in the system. Our theorem improves a previous result. Furthermore, our method can also be applied to dead with the case of multiple holes.展开更多
文摘We consider the covalence characters of the 3d electron with the eg orbital freedoms and put forward a new mechanism of the orbital ordering （00） based on the direct coulomb repulsion in this article. The results show that the orbital-orbital interaction （OO-I） between the adjacent ions in 180-degree configuration is dominated by the superexchange energy accompanied by a weak orbital-spin coupling, and the OO-I in 90-degree configuration is monitored by the oxygen on-site coulomb repulsion. The ferro-OO is the stable ground state for the one-dimensional chain in the case of the 90-degree configuration.
基金Supported by National Natural Science Foundation of China under Grant No.11374017
文摘In the present paper, we investigate the existence of ferromagnetism in a two-band Hubbard model, by applying a recently-introduced method by us to study ferromagnetism in metallic dusters. We prove rigorously that the ground state of this model is ferromagnetic if the intra-orbital Coulomb repulsion between electrons is infinitely strong and only one hole exists in the system. Our theorem improves a previous result. Furthermore, our method can also be applied to dead with the case of multiple holes.
