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Onset of charge incompressibility and Mott gaps in the honeycomb-lattice SU(4) Hubbard model: Lessons for twisted bilayer graphene systems
Physical Review B ( IF 3.7 ) Pub Date : 2022-06-23 , DOI: 10.1103/physrevb.105.l241410
Rahul Hingorani, Jaan Oitmaa, Rajiv R. P. Singh

We use finite-temperature strong coupling expansions to calculate thermodynamic properties of the honeycomb-lattice SU(4) Hubbard model. We present numerical results for various properties including chemical potential, compressibility, entropy and specific heat as a function of temperature and density at several U/t values. We study the onset of charge incompressibility and Mott gaps as the temperature is lowered at integer densities. In the incompressible Mott regime, the expansions are recast into a high-temperature expansion for a generalized spin model with SU(4) symmetry, which is then used to study the convergence of strong coupling expansions in t/U. We discuss lessons that can be drawn from high-temperature properties of a simple Hubbard model regarding twisted bilayer graphene and other magic-angle flat-band systems.

中文翻译:

蜂窝晶格 SU(4) Hubbard 模型中电荷不可压缩性和莫特间隙的开始:扭曲双层石墨烯系统的教训

我们使用有限温度强耦合展开来计算蜂窝晶格 SU(4) Hubbard 模型的热力学性质。我们提出了各种性质的数值结果,包括化学势、可压缩性、熵和比热,在几个条件下作为温度和密度的函数ü/价值观。我们研究了当温度以整数密度降低时电荷不可压缩性和莫特间隙的开始。在不可压缩的 Mott 状态下,膨胀被重铸为具有 SU(4) 对称性的广义自旋模型的高温膨胀,然后用于研究强耦合膨胀的收敛性/ü. 我们讨论了可以从关于扭曲双层石墨烯和其他魔角平带系统的简单 Hubbard 模型的高温特性中汲取的教训。
更新日期:2022-06-23
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