Ferromagnetism in the one-dimensional Hubbard model with orbital degeneracy: From low to high electron density
Abstract
We studied the one-dimensional Hubbard model with doubly-degenerate atomic orbitals by means of the density-matrix renormalization-group method and obtained the ground-state phase diagrams. It was found that ferromagnetism is stable from low to high (0<n<1.75) electron density when the interactions are sufficiently strong. Quasi-long-range order of triplet superconductivity was found coexisting with the ferromagnetic order for a strong Hund coupling region. At quarter-filling (n=1) the insulating ferromagnetic state appears accompanying orbital quasi-long-range order. For low densities (n1), the phase diagram of the ferromagnetic phase is similar to that obtained in infinite dimensions and this phase is robust against variation of the band-dispersion. In this case the double exchange mechanism is operative to stabilize the ferromagnetic order. A partially polarized state appears for 1.68<n<1.75 and phase separation occurs for n just below the half-filling (n=2).Keywords
All Related Versions
This publication has 0 references indexed in Scilit: