Effect of bond length and radius on superconducting transition temperature for FeAs-based superconductors  

作　　者：CHEN Ning 1 , LIU Yang 1 , JIA YaKui 1 , QU ShaoPeng 1 , ZHANG WanJie 1 & LI Yang 2 1 School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China 2 Department of Engineering Science and Materials, University of Puerto Rico at Mayaguez, Mayaguez PR 00681-9044, USA 

出　　处：《Science China(Physics,Mechanics & Astronomy)》2010年第1期59-63,共5页中国科学：物理学、力学、天文学（英文版）

基　　金：Supported by the National Science Foundation of USA (Grant No.DMR-0821284);the National Natural Science Foundation of China (Grant No. 50372005);the Natural Science Foundation of Beijing (Grant No.1072007)

摘　　要：By comparing the data of lattice parameters of more than 50 new FeAs-based high temperature superconductors in two syetems, the effect of bondlength on superconducting transition temperature (T C ) was found that, for both FeAs superconductor systems with similar ionic radii of cation A, the bond length L As-A between Arsenic atom and its nearest neighbor cation at the A site is in an inverse proportion to T C , i.e. the larger the bond length L As-A , the lower the T C . In addition, we also found a noticeable effect of ionic radius on T C , in which deviation from the tendency line of bond length vs. T C decreases with the increasing ionic radius. Both bond length-T C and ionic radii-T C relations indicate that the interaction of cation A and As ion have significant effect on superconductivity. The analysis on the electronic structure indicates that there exists the proximity of the secondary-outer p-orbit of the cation A and the 4s orbit of the As ion, both in energy space and in real space. Some high frequency individual vibrating modes would be established through exchange coupling on their inner orbits. It is worth of mention that the superconducting condensation is influenced by the interaction between the cation A and the As atoms.By comparing the data of lattice parameters of more than 50 new FeAs-based high temperature superconductors in two syetems, the effect of bondlength on superconducting transition temperature (T C ) was found that, for both FeAs superconductor systems with similar ionic radii of cation A, the bond length L As-A between Arsenic atom and its nearest neighbor cation at the A site is in an inverse proportion to T C , i.e. the larger the bond length L As-A , the lower the T C . In addition, we also found a noticeable effect of ionic radius on T C , in which deviation from the tendency line of bond length vs. T C decreases with the increasing ionic radius. Both bond length-T C and ionic radii-T C relations indicate that the interaction of cation A and As ion have significant effect on superconductivity. The analysis on the electronic structure indicates that there exists the proximity of the secondary-outer p-orbit of the cation A and the 4s orbit of the As ion, both in energy space and in real space. Some high frequency individual vibrating modes would be established through exchange coupling on their inner orbits. It is worth of mention that the superconducting condensation is influenced by the interaction between the cation A and the As atoms.

关 键 词：lattice constant FeAs-based SUPERCONDUCTOR SUPERCONDUCTING transition temperature 

分 类 号：O511[理学—低温物理]