高温超导体电子结构和超导机理的角分辨光电子能谱研究

超导是一种奇异的宏观量子现象.100多年来,已发现的超导体主要分为两类:以金属或者合金为代表的常规超导体以及以铜氧化物和铁基高温超导体为代表的非常规超导体.常规超导体的超导机理能被BCS超导理论完美解释,但高温超导体的超导机理至今仍未达成共识,已经成为凝聚态物理领域中长期争论且充满挑战的重大科学问题.从实验上揭示非常规超导材料的微观电子结构,是理解其奇异正常态和超导电性机理、建立新理论的前提和基础.角分辨光电子能谱技术,由于可以实现对材料中电子的能量、动量和自旋的直接测量,在高温超导研究中发挥了重要的作用.本文综述了我们利用角分辨光电子能谱技术在铜氧化物和铁基高温超导体电子结构和超导机理研究中取得的一些进展,主要包括母体的电子结构、正常态的非费米液体行为、超导态的能带和超导能隙结构以及多体相互作用等.这些结果为理解铜氧化物和铁基高温超导体的物性及超导机理提供了重要的信息.

Angle-resolved photoemission spectroscopy studies on the electronic structure and superconductivity mechanism for high temperature superconductors

Superconductivity represents a magic macroscopic quantum phenomenon.There have been two major categories of superconductors:the conventional superconductors represented by metals or alloys;and the unconventional superconductors represented by cuprates and iron-based high-temperature superconductors.While the superconductivity mechanism of the conventional superconductors is successfully addressed by the BCS theory of superconductivity,no consensus has been reached in understanding the high temperature superconductivity mechanism for more than 30 years,which has become one of the most prominent issues in condensed matter physics.Revealing the microscopic electronic structure of unconventional superconductors is the prerequisite and foundation in understanding their superconductivity.Angle resolved photoelectron spectroscopy(ARPES)plays an important role in the study of unconventional superconductors because it can directly measure the electronic structure of materials.In this paper,our recent progress in the ARPES study of electronic structure and superconductivity mechanism of high temperature cuprate superconductors and ironbased superconductors is reviewed.It mainly includes the electronic structure of the parent compound,the non-Fermi liquid behavior in the normal state,the band and gap structure of the superconducting state,and the many-body interactions both in the normal and superconducting states.These results will provide important information in understanding the superconductivity mechanism of Cu-based and Fe-based superconductors.