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Spin-orbital gap of multiorbital antiferromagnet

Hiroaki Onishi·Takashi Hotta
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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.

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Hiroaki Onishi, Takashi Hotta. 2006-07-24. Spin-orbital gap of multiorbital antiferromagnet. https://doi.org/10.1103/physrevb.75.014410

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