FOR 1700: Metallic Nanowires on the Atomic Scale: Electronic and Vibrational Coupling in Real World Systems

这个研究组的中心议题是在明确考虑2D和3D耦合的情况下，探索和识别具有一维属性的物理场景、它们的控制和它们的操纵。选择它的原因很明显：理想的一维(1D)电子系统吸引人的特殊性质，如电导量子化、电荷密度波(CDW)和Luttinger-Luttinger-Liquid行为，加上各种伴随着大量相变的不稳定性，只有在二维(2D)或三维(3D)相互作用的系统中才能实验观察到。除了在T&gT；0时稳定1D特性外，这些联轴器的受控修改还允许调节和改变1D行为。通过这种方式，我们试图通过实验小组和理论小组之间的密切合作，对这个非常有趣的领域有更深入的了解。金属原子线是由生长在Si或Ge表面上的Au、Pt、In或Pd自组织原子链组成的，以及用稀土元素或过渡金属形成的硅化物线，是我们关注的一维系统的原型。根据积累的经验，我们将继续研究导线中的结构和相变及其电子结构与电子输运、单粒子和集体激发以及它们的动力学之间的关系。在这一新的供资期间，重点将放在电线之间的耦合、与底层衬底的耦合以及3D嵌入材料的受控变化上。为此，我们计划通过原子和分子的吸附、台阶密度的变化、台阶取向和衬底的变化来操纵电荷密度、长程有序和局域结构。进一步强调了这些系统中出乎意料的大自旋有序度，它的稳定性和与其他参数的耦合。此外，声子和电子动力学以及光诱导相变也将发挥重要作用。实验和理论之间业已建立的密切合作以及应用于相同系统的各种实验方法的结合将继续并加强，以便全面探索这一领域。

The central topic of this Research Unit is the exploration and identification of physical scenarios with one-dimensional properties under explicit consideration of 2D and 3D coupling, their control and their manipulation. It was chosen for obvious reasons: The attractive special properties of ideal one-dimensional (1D) electronic systems such as quantization of conductance, charge-density waves (CDWs), and Luttinger-liquid behav- ior, coupled with a variety of instabilities with a wealth of associated phase transitions, are experimentally only observable in systems that interact in two (2D) or three (3D) dimensions. Apart from stabilization of 1D properties at T >0, controlled modification of these couplings allows tuning and changes also of the 1D behavior. In this way we try to obtain deeper insight into this highly interesting field by close collaboration between experimental and theoretical groups. Metallic atomic wires, consisting of self-organized atomic chains of Au, Pt, In or Pb grown on Si or Ge surfaces, as well as silicide wires, formed with rare earth elements or transition metals, are prototype 1D systems, on which we concentrate. Based on the gathered experience, we will continue to correlate studies of structure and phase transi- tions in the wires and their electronic structure with electronic transport, single particle and collective excitations as well as with their dynamics. In this new funding period, a focus will be put on the controlled variation of coupling between wires, coupling to the underlying substrate and to the 3D embedding material. For this purpose, we plan to ma- nipulate charge densities, long range order and local structure by adsorption of atoms and molecules, variation of step densities, step orientations and substrates. Further emphasis will be given to the unexpected large degree of spin order in these systems, its stability and coupling to other parameters. Furthermore phonon and electron dynamics will play an important role as well as photoinduced phase transitions. The already well established close collaboration between experiment and theory as well as the combination of various experimental methods applied to identical systems will be continued and intensified in order to explore this field comprehensively.