Second magnetization peak effect, vortex dynamics, and flux pinning in 112-type superconductor Ca0.8La0.2Fe1-xCox As2

作者：Zhou, Wei; Xing, Xiangzhuo; Wu, Wenjuan; Zhao, Haijun; Shi, Zhixiang^*

来源：Scientific Reports, 2016, 6(1): 22278.

DOI：10.1038/srep22278

• CRITICAL-CURRENT DENSITY
• CREEP
• RELAXATION
• MECHANISMS
• LATTICE

Investigation of vortex pinning and its relaxation is of great importance for both basic physics and technological applications in the field of superconductivity. We report a great improvement of superconducting properties in the recently discovered 112-type superconductors (Ca, La)FeAs2 through Co co-doping. High critical current density J(s)(5 K) > 2*10(6) A/cm(2) is obtained and pronounced second peak effect is observed in magnetization hysteresis loops. Both the dynamic and static relaxation studies result in comparable and sizable relaxation rates S or Q, indicating a fast vortex creep. The second magnetization peak (SMP) is found to be strongly associated with a crossover from elastic to plastic vortex creep. Above the crossover, plastic vortex creep governs the vortex dynamics in a wide range of temperatures and fields. A good scaling behavior of the normalized pinning force density f(p) by formula f(p) = h(p)(1-h)(q) ((p) = 1.44, q = 1.66, h = 0.44) is revealed, which demonstrates an important contribution from core normal point-like pinning sites. To better understand the SMP phenomenon, we discuss the related physical scenario as well as the affecting factors in the SMP occurrence.

• 出版日期2016-3-7
• 单位东南大学