Coherent propagation and decay of quasi-particles

准粒子的相干传播和衰变

• 批准号: 471475967
• 负责人: Professor Dr. Maurits Haverkort
• 金额: --
• 依托单位: Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/471475967?language=en
• 关键词: Coherent; propagation; decay; quasi; particles

We will develop a real-space / momentum, real-time / frequency Green's function method to describe the decay of quasi-particles in the dynamics of realistic materials as seen in local and non-local $n$-point correlation functions. The focus will be on the decay due to charge scattering for either low energy excitations (magnons) or high energy excitations (x-ray induced excitons and resonances). Project P7 directly contributes to thread 3 on dynamical properties of correlated models and materials in excited states.We will extend the methods in our program package Quanty to calculate the dynamics of x-ray excited core states, and low energy magnetic and orbital excitations to include a material specific self-energy describing the decay. We will focus on correlated metals relevant within QUAST such as, Ce3Bi4Pd3, CeRu4Sn6, Co3Sn2S2, CeBa7Au4Si40 and TaS2 experimentally investigated within P1, P3, and P6. We will use LDA+DMFT as a starting point for the electronic structure calculations. We will implement methods to calculate the change in the dynamics of x-ray core excited states as a result of the Auger-Meitner decay due to Coulomb scattering of local electrons into the continuum. In order to evade excessively large Hilbert spaces, we will implement the Coulomb scattering into non-local states as a self-energy for the electronic propagation of the quasi-particle. The propagating quasi-particle in the case of x-ray excitations is a core-hole - valence-electron exciton. Having a non-zero self-energy makes the description of the dynamics easier as the system forgets long-time behaviour. We can test our methods by comparing 2- and 4-point correlation functions to the x-ray absorption and resonant inelastic x-ray scattering of the model correlated metals measured (P1) and calculated (P1, P5) within QUAST. After we understand how to treat the self-energy of core excited states we will implement the self-energy of low energy magnetic excitations due to charge scattering. In the frequency domain this allows one to not only obtain an energy momentum dispersion of magnetic excitations in materials like Ce3Bi4Pd3, CeRu4Sn6, Co3Sn2S2 and CeBa7Au4Si40 but also their line widths. In the time domain the self-energy sets a time scale for the transfer of excitation energy between the spin and charge degrees of freedom of the material. Thereby setting time scales for the equilibration of the slow spin dynamics (P8).

我们将开发一种实空间/动量、实时/频率格林函数方法来描述真实材料动力学中准粒子的衰变，如局部和非局部$n点关联函数所见。焦点将集中在低能激发(磁子)或高能激发(x射线诱导的激子和共振)的电荷散射引起的衰变。P7项目直接贡献于主题3关于相关模型和材料在激发态下的动力学性质。我们将扩展我们程序包Quantity中的方法来计算x射线激发核态、低能磁激发和轨道激发的动力学，以包括描述衰变的材料比自能。我们将专注于Quast中相关的金属，如在P1、P3和P6中实验研究的Ce3Bi4Pd3、CeRu4Sn6、Co3Sn2S2、CeBa7Au4Si40和TaS2。我们将使用LDA+DMFT作为电子结构计算的起点。我们将实现一些方法来计算由于局域电子在连续介质中的库仑散射而引起的俄歇-迈特纳衰变引起的x射线核激发态的动力学变化。为了避免过大的希尔伯特空间，我们将库仑散射实现为准粒子电子传播的自能。在X射线激发的情况下，传播的准粒子是一个核-空穴-价电子激子。当系统忘记长期行为时，拥有非零的自能使得描述动力学变得更容易。我们可以通过将两点和四点关联函数与Quast中测量(P1)和计算(P1，P5)的模型关联金属的X射线吸收和共振非弹性X射线散射进行比较来测试我们的方法。在我们了解了如何处理核心激发态的自能之后，我们将实现由于电荷散射而引起的低能磁激发的自能。在频域中，这不仅可以得到Ce3Bi4Pd3、CeRu4Sn6、Co3Sn2S2和CeBa7Au4Si40等材料中磁激发的能量动量色散，而且还可以得到它们的线宽。在时间域中，自能为激发能在材料的自旋自由度和电荷自由度之间的转移设定了一个时标。从而设置用于慢自旋动力学平衡的时间刻度(P8)。