铁基超导体磁激发的共振非弹性X射线散射研究  

Magnetic excitations in iron-based superconductors as revealed by resonant inelastic X-ray scattering

作　　者：刘瑞鲜 张文婷 鲁兴业 LIU RuiXian;ZHANG WenTing;LU XingYe(Department of Physics,Beijing Normal University,Beijing 100875,China)

机构地区：[1]北京师范大学物理学系,北京100875

出　　处：《中国科学：物理学、力学、天文学》2023年第12期131-143,共13页Scientia Sinica Physica,Mechanica & Astronomica

基　　金：国家自然科学基金(编号:11922402,12174029)资助项目。

摘　　要：在铁基超导材料中,超导电性通常起源于对反铁磁母体的载流子掺杂.随着掺杂量的增加,反铁磁长程序逐渐被抑制,超导出现并在反铁磁序消失的边缘达到最佳Tc.在最佳和过掺杂区域,虽然已经不存在任何反铁磁长程序,但仍然存在很强的反铁磁涨落.在铜氧化物和铁基高温超导体中,很多实验证据表明自旋为1的反铁磁涨落极有可能是超导电子配对的媒介,而驱动这一配对的则是电子间的反铁磁关联.因此,从实验上研究铁基超导体的磁激发谱及其对掺杂的依赖关系,获得反铁磁关联能等信息,对理解铁基超导的微观机制至关重要.在过去十几年中,非弹性中子散射(Inelastic Neutron Scattering,INS)在测定铁基超导材料中的磁激发方面发挥了主导作用.在过去十年中,共振非弹性X射线散射(Resonant Inelastic X-ray Scattering,RIXS),作为一种可以测量过渡族金属化合物中磁激发的实验技术,被用于铁基超导体中磁激发及其演化的研究.由于RIXS具有元素敏感、价态敏感、光通量高等优点,在铁基超导材料磁激发的相关研究中,发挥了独特的作用.本文从RIXS的特点出发,回顾了铁基超导体中磁激发的RIXS研究结果,讨论了RIXS在进行这些研究时表现出的优势和不足.通过这些讨论,本文强调了在铁基超导体元激发的研究中,利用RIXS独特优势的重要性.In iron-based superconductors(FeSCs),superconductivity is usually induced by doping charge carriers into the antiferromagnetic(AF)parent compounds.With the increase of doping,the long-range AF order is gradually suppressed,while the superconductivity emerges and reaches its optimal Tc near the border of the AF order.Though long-range AF order is completely suppressed near optimal doping,strong AF spin fluctuations persist in the optimal and overdoped regime.Numerous experimental evidence in copper-oxide and iron-based high-Tc superconductors suggested that S=1 AF spin fluctuation is the leading candidate“pairing glue”(driven by spin-spin interactions)for mediating high-Tc superconductivity.Hence,it is crucial to study magnetic excitation and its doping dependence in FeSCs,which can be used to determine the magnetic interactions and provide key insights into understanding the microscopic mechanism of iron-based high-Tc superconductivity.Since the discovery of FeSCs,inelastic neutron scattering(INS)has played a crucial role in measuring the magnetic excitations in FeSCs.As a powerful probe of elementary magnetic excitations in transition-metal compounds,resonant inelastic X-ray scattering(RIXS)has been used to study the magnetic excitations in FeSCs in the past decade.Since RIXS specifies a high-flux,and has the sensitivity for element and valence-state,this technique plays a unique role in studying the magnetic excitations in FeSCs.In this review,we present the research progress concerning the RIXS study of the magnetic excitations in FeSCs,and discuss the advantages and disadvantages of RIXS.We emphasize that it is important to take advantage of the unique aspects of RIXS in studying the elementary excitations in FeSCs.

关 键 词：铁基超导 磁激发 共振非弹性X射线散射 关联电子材料 

分 类 号：O469[理学—凝聚态物理]