论文标题
重新归一化和非热性对强相关电子系统非线性响应的影响
Effects of renormalization and non-Hermiticity on nonlinear responses in strongly-correlated electron systems
论文作者
论文摘要
深入研究了冷凝物质中的非线性响应，因为它们提供了有关材料的丰富信息，并将其应用于二极管或高频光学设备。尽管广泛探讨了非互动模型中的非线性响应，但强相关性对非线性响应的影响仍然很少了解，尽管已经提出相关性可以增强非线性响应。在这项工作中，我们首先在有限温度下使用绿色功能方法对非线性响应进行了分析推导。然后，我们讨论使用常规方法（例如降低密度矩阵方法）考虑耗散的困难。我们透露，在考虑光学响应时，松弛时间近似会导致严重的局限性。最后，我们证明了相关效应，例如轨道结构的重新归一化和轨道或sublattices中不同的寿命，可以显着增强非线性响应，甚至可以改变非线性电导率的迹象。
Nonlinear responses in condensed matter are intensively studied because they provide rich information about materials and hold the possibility of being applied in diodes or high-frequency optical devices. While nonlinear responses in noninteracting models have been explored widely, the effect of strong correlations on the nonlinear response is still poorly understood, even though it has been suggested that correlations can enhance the nonlinear response. In this work, we first give an analytical derivation of nonlinear responses using the Green's function methods at finite temperature. Then, we discuss the difficulties of considering dissipation using conventional methods, such as the reduced density matrix method. We reveal that the relaxation time approximation leads to severe limitations when considering optical responses. Finally, we demonstrate that correlation effects, such as the renormalization of the band structure and different lifetime in orbitals or sublattices, can significantly enhance nonlinear responses and can even change the sign of the nonlinear conductivity.
