Spin-orbital gap of multiorbital antiferromagnet

Abstract

In order to discuss the spin-gap formation in a multiorbital system, we analyze an e_g-orbital Hubbard model on a geometrically frustrated zigzag chain by using a density-matrix renormalization group method. Due to the appearance of a ferro-orbital arrangement, the system is regarded as a one-orbital system, while the degree of spin frustration is controlled by the spatial anisotropy of the orbital. In the region of strong spin frustration, we observe a finite energy gap between ground and first-excited states, which should be called a spin-orbital gap. The physical meaning is clarified by an effective Heisenberg spin model including correctly the effect of the orbital arrangement influenced by the spin excitation.

8 pages, 6 figures, extended version

References in corpus (5)

• The density-matrix renormalization group
• Orbital ordering phenomena in $d$- and $f$-electron systems
• Suppression of Spin Frustration due to Orbital Selection
• Key Role of Orbital Anisotropy in Geometrically Frustrated Electron System
• Spin-charge-orbital ordering on triangle-based lattices