非均匀团簇DMFT研究Hubbard晶格中p-n结Mott能隙闭合
Inhomogeneous cluster DMFT study on p-n junction Mott gap closing in Hubbard lattice
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中文总结 AI 辅助
本研究通过正方晶格Hubbard模型和动力学平均场理论，研究了p-n结中电势梯度导致的Mott能隙闭合，发现金属相在电势降接近激发能时占优，且激发能几乎与方向无关，为实验阈值提供了理论解释。
中文摘要 AI 辅助
通过考虑正方晶格上的Hubbard模型，研究了由外部电势梯度诱导的Mott能隙闭合。我们的模型由空穴掺杂和电子掺杂区域构成p-n结，其中局域势在界面间平滑变化。通过动力学平均场理论框架内描述非均匀2x2 plaquette杂质团簇的关联效应，研究了电势降方向（沿正方形边或沿对角线）的影响。研究发现，当电势降变得与开放2x2 plaquette的基态与第一激发态之间的能量本征值差相当时，金属相优于Mott绝缘体。在相同的相关电场强度下，激发能几乎与电势降方向无关，在U=5.8t（跳跃参数为t）时约为0.35t。在绝缘体-金属转变时，关联金属在零能量处表现出相干峰，其强度在电势降沿正方形对角线时大于沿边时。主要原因归因于前一种情况下两个分子轨道的简并性得以保留，而后者则经历能级分裂。我们的结果与实验测量的Mott能隙闭合阈值进行了讨论。
英文摘要
Mott gap closing induced by an external potential gradient is studied by considering the Hubbard model on a square lattice. Our model consists of hole- and electron-doped domains forming the p-n junction where the on-site potential varies smoothly across the interface. The effect of the potential drop direction, either along square edge or diagonal, is studied by describing the correlation effects of inhomogeneous 2x2 plaquette impurity clusters within a dynamical mean-field theory framework. It is found that the metallic phase is favored over the Mott insulators when the potential drop becomes comparable to the energy eigenvalue difference of an open 2x2 plaquette between the ground state and the first excited state. Given the same associated electric-field strength, the excitation energy is almost independent of the drop direction, which amounts ~0.35t at U=5.8t with the hopping parameter t. Upon insulator-to-metal transition, the correlated metal exhibits a coherent peak at zero energy whose intensity is greater for the drop direction along the square diagonal than along the edge. The main origin is attributed to the preserved degeneracy of two molecular orbitals for the former case, while it undergoes splitting in the energy levels for the latter. Our result is discussed regarding the experimentally measured Mott gap closing thresholds.
发表机构
- Ulsan National Institute of Science and Technology（蔚山国立科学技术研究院）
- Pohang University of Science and Technology (POSTECH)（浦项科技大学）
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