Development of high-Tc iron-based superconductors using co-doping and study on the mechanism of the increase in Tc induced by this method

2015 Fiscal Year Final Research Report

• Project/Area Number: 25400372
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Okayama University
• Principal Investigator: Kudo Kazutaka 岡山大学, 自然科学研究科, 准教授 (40361175)
• Project Period (FY): 2013-04-01 – 2016-03-31
• Keywords: 高温超伝導

Outline of Final Research Achievements

In iron-based arsenides, systematic studies on chemical doping have led to the highest superconducting transition temperature Tc of 55 K in SmFeAsO1-xFx among 1111-type compounds and 38 K in Ba1-xKxFe2As2 among 122-type compounds. It seems that there is no room left for enhancement of Tc in terms of chemical doping. Here, in this research project, we studied the mechanism of the increase in Tc up to 45 K in La and P co-doped 122-type CaFe2As2. Our result revealed that the superconducting phase is far from the antiferromagnetic phase in the co-doped CaFe2As2, and also suggested that the fluctuation between forming and breaking As2 dimers could be responsible for the emergence of superconductivity. Moreover, we found that co-doping also enhances Tc in the 112-type Ca1-xRExFeAs2. The additional doping of Sb increases the Tc of Ca1-xLaxFeAs2 from 35 to 47 K. These results suggested that the co-doping sheds light on a novel route to develop iron-based superconductors with higher Tc.

Free Research Field

数物系科学