期刊
PHYSICAL REVIEW B
卷 84, 期 7, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.84.075450
关键词
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资金
- Special Coordination Funds for Promoting Science and Technology (SCF)
- Scientific Research on Innovative Areas [20110002]
- Ministry of Education, Culture, Sports, Science and Technology in Japan [19740205, 22540366, 23540403]
- NANOSIM-GRAPHENE project [ANR-09-NANO-016-01, ANR/P3N2009]
- Grants-in-Aid for Scientific Research [20110002, 19740205, 23540403, 22540366] Funding Source: KAKEN
We reexamine the band structure of the stripe charge ordered state of alpha-(BEDT-TTF)(2)I-3 under pressure by using an extended Hubbard model within the Hartree mean-field theory. By increasing pressure, we find a topological transition from a conventional insulator with a single-minimum in the dispersion relation at the M point in the Brillouin zone, toward a new phase which exhibits a double minimum. This transition is characterized by the appearance of a pair of Dirac electrons with a finite mass. Using the Luttinger-Kohn representation at the M point, it is shown that such a variation of the band structure can be described by an effective 2 x 2 low-energy Hamiltonian with a single driving parameter. The topological nature of this transition is confirmed by the calculation of the Berry curvature which vanishes in the conventional phase and has a double peak structure with opposite signs in the new phase. We compare the structure of this transition with a simpler situation which occurs in two-component systems, like boron-nitride.
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