Unusual Finite-Temperature Phase Diagram for Semi-hard-core Bosons in Two Dimensions

详细信息    查看全文

• 作者：V. V. Konev ; Yu. D. Panov ; A. V. Korolev…
• 关键词：Semi ; hard ; core bosons ; On ; site correlations ; Reentrant transition
• 刊名：Journal of Low Temperature Physics
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：185
• 期：5-6
• 页码：680-685
• 全文大小：486 KB
• 刊物类别：Physics and Astronomy
• 刊物主题：Physics
  Condensed Matter
  Characterization and Evaluation Materials
  Magnetism and Magnetic Materials
  
• 出版者：Springer Netherlands
• ISSN：1573-7357
• 卷排序：185

文摘

The extended bosonic Hubbard model (EBHM) is a paradigmatic model for the highly topical field of ultracold gases in optical lattices. Using quantum Monte Carlo simulations, we have determined the finite-temperature phase diagram of the EBHM with truncation of the on-site Hilbert space to the three lowest occupation states: n = 0, 1, 2 (semi-hard-core boson Hubbard model) given nearest-neighbor repulsion, however, both positive and negative values of the on-site boson–boson coupling U. This model is equivalent to an anisotropic spin-1 XXZ model (\(n=S_z+1\)) in a magnetic field. In the limit of large negative U (the boson–boson attraction), the model turns into the well-known model of hard-core bosons whose rich phase diagram demonstrates several puzzling features, in particular, signatures of an unusual reentrant behavior with a charge ordering upon increasing the temperature. We have shown that the rise of the correlation parameter U to positive values (the boson–boson repulsion) expectedly leads to a lowering of the temperature of the superfluid transition and unexpectedly to the more and more pronounced “reentrance” effect.