时间分辨角分辨光电子能谱对高温超导体Bi2(Sr2-xLax)CuO6+d电子结构的研究

Since being discovered the high temperature superconductors (HTSC) is a central mystery in the condensed matter physics. The physics underlying the superconductivity and abnormal normal states remains elusive after nearly 30 years intensive research. Especially, we are lacking in understanding of the Fermi surface topology. In the normal state of the high-transition-temperature copper oxide superconductors, angle-resolved photoemission (ARPES) measurements have seen Fermi arcs—that is, open-ended gapless sections in the large Fermi surface—rather than a closed loop expected of an ordinary metal. As the development of the equipment, Fermi pockets were suggested by quantum oscillation and ARPES measurements. Because the electronic structure is too complicated, that ARPES has failed in providing the "smoking gun" evidence on the existence of Fermi pockets. Here, we proposed to perform system research on the nature of the superconducting and abnormal normal states of various doped HTSC single crystals Bi2(Sr2-xLax)CuO6+d by utilizing time-resolved and angle-resolved photoemission spectroscopy. The study will be focused on the doping and temperature evolution of the Fermi surface topology. This work is designed to provide important information about the nature of superconductivity. It will help to find new superconductors with a higher transition temperature.

高温超导体自从被发现已经就一直是凝聚态物理研究的核心课题。经过快三十年年的努力，对于其超导机理和反常正常态行为背后的物理仍然没有答案。特别的对于其费米面的拓扑结构的认识非常缺乏。在铜氧化物高温超导体的正常态，早期的角分辨光电子能谱测量发现了费米弧------大的费米面中的无能隙区域，这不同于普通金属中的闭环。后来随着实验技术的发展，量子振荡和角分辨光电子能谱实验都在高温超导体中发现了费米口袋存的证据。但是由于铜氧化物高温超导体电子结构的复杂性，角分辨光电子能谱没有能够观测到费米口袋存在的决定性证据。这里我们计划采用高时间分辨率的时间分辨角分辨光电子能谱仪对不同掺杂浓度的铜氧化物高温超导体Bi2(Sr2-xLax)CuO6+d的电子结构进行详细和深入的研究。研究将集中在费米面拓扑结构随掺杂浓度和温度的演化。本课题的研究将为理解高温超导电性提供关键信息，帮助寻找新的更高超导转变温度的超导体。