Superconducting Stiffness and Coherence Length of FeSe 0.5 Te 0.5 Measured in a Zero-Applied Field

Condensed Matter

article

Amotz Peri¹  Itay Mangel¹  Amit Keren¹ 

[1] Department of Physics, Technion-Israel Institute of Technology

关键词: superconductivity;    iron-based superconductors;    magnetism;    stiffness;    coherence length;    Fe1+ySexTe1−x;   

DOI  :  10.3390/condmat8020039

学科分类：社会科学、人文和艺术（综合）

来源: mdpi

【 摘 要 】

Superconducting stiffness ρ s and coherence lengthξare usually determined by measuring the penetration depthλof a magnetic field and the upper critical field Hc 2of a superconductor (SC), respectively. However, in magnetic SC, which is iron-based, this could lead to erroneous results, since the internal field could be very different from the applied one. To overcome this problem in Fe1 + y Se xTe1 − xwith x ∼ 0.5 and y ∼ 0 (FST), we measured both quantities with the Stiffnessometer technique. In this technique, one applies a rotor-free vector potentialAto a superconducting ring and measures the current densityjvia the ring’s magnetic momentm . ρ s andξare determined from London’s equation, j = −ρ sA, and its range of validity. This method is particularly accurate at temperatures close to the critical temperature T c. We find weaker ρ s and longerξthan existing literature reports, and critical exponents which agree better with expectations based on the Ginzburg–Landau theory.

【 授权许可】

CC BY