铁基超导1111体系CaFeAsF的单晶生长和物性研究

自2008年发现铁基高温超导以来,人们对该体系的材料探索和物理性质开展了广泛而深入的研究.然而,作为最早被发现并且体材料中临界转变温度最高的一大类材料, 1111体系长期以来一直缺乏大尺寸高质量的单晶样品,这严重制约了对这一材料体系相关物理问题的深入研究.最近几年,氟基的1111体系材料CaFeAsF的单晶生长取得了较大进展:以CaAs作为助熔剂,在常压下成功地生长出了毫米尺寸高质量的CaFeAsF母体以及Co掺杂的超导体单晶;在此基础上,多个研究组利用不同实验手段对该体系的物理性质进行了研究,并得到了一些比较重要的结果.本综述对该方向的进展进行初步总结,内容涵盖晶体生长、各向异性、强场下的磁阻、磁力矩、红外光谱、高压调控、量子振荡等内容.

Single crystal growth and physical property study of 1111-type Fe-based superconducting system CaFeAsF

Since Fe-based high temperature superconductor was discovered in 2008, its material exploration and physical properties have been widely and in depth studied. However, the 1111 system, which was discovered first to have the highest T_c in the bulk material, has long been lacking in large-size and high-quality single-crystalline sample. This seriously restricts the in-depth study of the physical problems relating to this material system. In recent years, the great progress of single crystal growth of the fluorine-based 1111 system CaFeAsF has been made. One has successfully grown the high-quality CaFeAsF parent phase and Co doped superconducting single crystal with millimeter size at ambient pressure by using CaAs as the flux. On this basis, several research groups have studied the physical properties of this system by different experimental means and obtained some important results. For example, Dirac Fermions have been detected in CaFeAsF single crystal by measuring the quantum oscillation and optical conductivity. A high-field-induced metal-insulator transition was reported in CaFeAsF, which is closely related to the quantum limit. This review is intended to make a preliminary summary of the progress of this area, including crystal growth, quantum oscillation, infrared spectrum, magnetoresistance under strong field, high pressure regulation, anisotropy, superconducting fluctuations, etc.