Effects of Long-Range Correlations on Nonmagnetic Mott Transitions in Hubbard model on Square Lattice
| Autor: | Miyagawa, Tomoaki, Yokoyama, Hisatoshi |
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| Rok vydání: | 2011 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1143/JPSJ.80.084705 |
| Popis: | The mechanism of Mott transition in the Hubbard model on the square lattice is studied without explicit introduction of magnetic and superconducting correlations, using a variational Monte Carlo method. In the trial wave functions, we consider various types of binding factors between a doubly-occupied site (doublon, D) and an empty site (holon, H), like a long-range type as well as a conventional nearest-neighbor type, and add independent long-range D-D (H-H) factors. It is found that a wide choice of D-H binding factor leads to Mott transitions at critical values near the band width. We renew the D-H binding picture of Mott transitions by introducing two characteristic length scales, the D-H binding length l_{DH} and the minimum D-D distance l_{DD}, which we appropriately estimate. A Mott transition takes place at l_{DH}=l_{DD}. In the metallic regime (l_{DH}>l_{DD}), the domains of D-H pairs overlap with one another, thereby doublons and holons can move independently by exchanging the partners one after another. In contrast, the D-D factors give only a minor contribution to the Mott transition. Comment: 13 pages, 18 figures, submitted to J. Phys. Soc. Jpn |
| Databáze: | arXiv |
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