Resistance fluctuations in superconducting KxFe2-ySe2 single crystals studied by low-frequency noise spectroscopy

• 作者: Hai Zi Yuan Yao Ming-Chong He Di Ke Hong-Xing Zhan Yu-Qing Zhao Hai-Hu Wen Cong Ren
• 来源期刊: 中国物理B（英文版）
• 年，卷（期）: 2021,（4）
• 所属期刊栏目: CONDENSED MATTER:ELECTRONIC STRUCTURE,ELECTRICAL,MAGNETIC,AND OPTICAL PROPERTIES
• 页码范围: 571-577
• 页数: 7页
• 语种: 英文
• DOI: 10.1088/1674-1056/abf103

摘要

Low-frequency resistance noise spectroscopy is applied to investigate bulk single crystals of the intercalated iron-selenide KxFe2-ySe2 superconductors with different iron vacancy orders.Based on a generalized fluctuation model,the well-observed resistance hump above 100 K is interpreted as an insulator-metal phase transition with a characteristic tran-sition energy of 0.1-0.6 eV,indicating a highly inhomogeneous energy distribution configuration.In the superconducting transition regime,we find that the normalized resistance noise scales with resistance R excellently as SR/R2 ∝Rlrs with the noise exponent lrs ≈ 1.4.With reduced iron vacancy disordering in enhanced superconductivity KxFe2-ySe2 crystals,the level of resistance fluctuations is greatly suppressed,suggesting a geometrical phase transition for conduction channel,which is directly related to the microstructure of the crystals.