Critical Current Density and Vortex Dynamics in Fe(Te,Se) Annealed in Various Atmosphere
Critical Current Density and Vortex Dynamics in Fe(Te,Se) Annealed in Various Atmosphere
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DOI：
10.1109/tasc.2016.2542000
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发表时间：
2016-03
影响因子：
1.8
通讯作者：
T. Tamegai;Yue Sun;Tatsuhiro Yamada;S. Pyon
中科院分区：
文献类型：
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作者：
T. Tamegai;Yue Sun;Tatsuhiro Yamada;S. Pyon
由于过量铁的存在，生长的Fe(Te，Se)晶体没有表现出大块超导电性。在合适的气氛中进行热处理，可以去除有害的过剩铁，使它们成为块状超导体。报道了Fe1+y(Te0.6Se0.4)晶体在硫族(O2，S，Se，Te)和镍(P，As，Sb)气氛中的退火效应。结果表明，不同药剂对总铁的最佳摩尔比是不同的，说明不同的除铁机理是可行的。详细研究了优化退火态晶体的正常态和超导性质。临界电流密度及其弛豫测量表明，Fe1+y(Te0.6Se0.4)中的涡旋动力学符合集体蠕变理论。对不同温度下临界电流随时间演化的详细分析表明，Fe_(1+y)(Te_(0.6)Se_(0.4))中的涡旋钉扎是Δ_c钉扎和Δ-L钉扎共同作用的结果。
As-grown crystals of Fe(Te,Se) do not show bulk superconductivity due to the presence of excess irons. Annealing in an appropriate atmosphere can remove harmful excess irons and make them bulk superconductors. We report the effects of annealing on Fe1+y(Te0.6Se0.4) crystal in chalcogen (O2, S, Se, Te) and pnictogen (P, As, Sb) atmospheres. It is found that the optimal molar ratios of agents to the total irons are different for different agents, indicating that different mechanisms for the removal of excess irons are operative. The normal state and superconducting properties of optimally annealed crystal are carefully investigated. Critical current density and its relaxation measurements clarified that the vortex dynamics in Fe1+y(Te0.6Se0.4) is described by collective creep theory. Detailed analyses of the temporal evolution of the critical current at various temperatures clarified that the pinning of vortices in Fe1+y(Te0.6Se0.4) is a combination of ΔTc and Δl pinnings.