期刊
NEW JOURNAL OF PHYSICS
卷 12, 期 -, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/1367-2630/12/9/093021
关键词
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资金
- National Natural Science Foundation of China
- National Basic Research Program of China [2009CB929204]
- MOE of China [B06011]
- RGC CUHK [402107]
We investigate the quantum phase transitions in the half-filled ionic Hubbard model on a two-dimensional (2D) square lattice using the variational cluster approach (VCA). We present explicit evidence for the tendency toward a novel intermediate phase in this model. This phase is characterized by bond-located magnetization. For weak Coulomb repulsion U, the system is a band insulator, and then undergoes a transition to the intermediate phase at the first-phase boundary U = U-c1. As U is increased beyond the second transition point U-c2, there occurs a Mott insulator accompanied by a long-range antiferromagnetic (AF) order. The bond-located spin density wave competes with the antiferromagnetism while the charge-density modulation exists all the way due to the staggered potential Delta.
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