Charge and pairing dynamics in the attractive Hubbard model: Mode coupling and the validity of linear-response theory
Charge and pairing dynamics in the attractive Hubbard model: Mode coupling and the validity of linear-response theory
复制标题
有吸引力的哈伯德模型中的电荷和配对动力学：模式耦合和线性响应理论的有效性
DOI：
10.1103/physrevb.96.245139
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发表时间：
2017
影响因子：
3.7
通讯作者：
G. Seibold
中科院分区：
文献类型：
--
作者：
J. Bünemann;G. Seibold
泵浦-探测实验已被证明是研究各种材料中竞争有序动力学的有力工具。对数据的相应分析通常依赖于推广到非平衡情况的标准线性响应理论。在这里，我们考察了这种方法对具有电荷密度波和(或)超导(SC)序的系统的电荷和配对响应的有效性。我们的研究是基于我们在含时Hartree-Fock近似下研究的吸引人的Hubbard模型。特别是，我们计算了Sc和电荷序参数的失超和泵浦-探测动力学，以分析频谱和探测场与特定激发的耦合。我们的计算表明，在纯电荷有序基态的情况下，“线性响应假设”对于小到中等的非平衡情况(即泵浦脉冲)是合理的。然而，超导基态顶部的泵浦-探测动力学是由远离平衡态耦合的相位模和振动模决定的，这表明线性响应假设是失败的。
Pump-probe experiments have turned out as a powerful tool in order to study the dynamics of competing orders in a large variety of materials. The corresponding analysis of the data often relies on standard linear-response theory generalized to nonequilibrium situations. Here we examine the validity of such an approach for the charge and pairing response of systems with charge-density wave and (or) superconducting (SC) order. Our investigations are based on the attractive Hubbard model which we study within the time-dependent Hartree-Fock approximation. In particular, we calculate the quench and pump-probe dynamics for SC and charge order parameters in order to analyze the frequency spectra and the coupling of the probe field to the specific excitations. Our calculations reveal that the “linear-response assumption” is justified for small to moderate nonequilibrium situations (i.e., pump pulses) in the case of a purely charge-ordered ground state. However, the pump-probe dynamics on top of a superconducting ground state is determined by phase and amplitude modes which get coupled far from the equilibrium state indicating the failure of the linear-response assumption.