Magnetic and electric phase transitions in the Hubbard model |
| |
Authors: | E V Shipitsyn |
| |
Institution: | (1) Bogdanov International Institute, Yekaterinburg, 620062, Russia |
| |
Abstract: | Within the Hubbard model, two boson Green’s functions that describe the propagation of collective excitations of the electronic system—magnons (states with a single electron spin flip) and doublons (states with two electrons at one site of the crystal lattice)—are calculated for a Coulomb interaction of arbitrary strength and for an arbitrary electron concentration by applying a decoupling procedure to the double-time X-operator Green’s functions. It is found that the magnon and doublon Green’s functions are similar in structure and there is a close analogy between them. Instability of the paramagnetic phase with respect to spin ordering is investigated using the magnon Green’s function, and instability of the metallic phase to charge ordering is analyzed with the help of the doublon Green’s function. Criteria for the paramagnet-ferromagnet and metal-insulator phase transitions are found. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|