Two energy gaps in superconducting Lub>2b>Feb>3b>Sib>5b> single crystal derived from the temperature dependence of lower critical field Hb>cb>b>1b>(T)

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• 作者：J. Ge^a ; J. Gutierrez^a ; B. Raes^a ; T. Watanabe^b ; J. Koshio^b ; V.V. Moshchalkov^a ; ^{Victor.Moshchalkov@fys.kuleuven.be}
• 关键词：Lower critical field ; Penetration depth ; Two-gap superconductors
• 刊名：Physica C
• 出版年：2012
• 期刊代码：80_09214534
• 类别：ms
• 出版时间：August, 2012
• 卷：478
• 期：Complete
• 页码：5-9
• 文件大小：415 K

摘要

We report a detailed study of in-plane lower critical field Hb>cb>b>1b>(T) and penetration depth 位b>abb>(T) of the Lub>2b>Feb>3b>Sib>5b> superconductor. Two pronounced changes of the Hb>cb>b>1b> curvature are observed on the Hb>cb>b>1b>(T) curve around 0.4Tb>cb> and 0.65Tb>cb>, respectively, which are attributed to the two-band nature of superconductivity in Lub>2b>Feb>3b>Sib>5b>. The penetration depth of 位b>abb>(T) follows a power law (鈭?em>Tⁿ) below 0.4Tb>cb>, with n = 2.5 close to the values reported for the FeAs-pnictides, suggesting possible sb>卤b>-wave pairing in Lub>2b>Feb>3b>Sib>5b>. Temperature dependence of Hb>cb>b>1b> can be well fitted by the two-gap BCS model in the full temperature region using two superconducting gaps 螖b>1b> = 0.19 卤 0.1 meV and 螖b>2b> = 1.02 卤 0.1 meV.