Evidence for a nodal energy gap in the iron-pnictide superconductor LaFePO from penetration depth measurements by scanning SQUID susceptometry

We measure changes in the penetration depth lambda of the T_{c} approximately 6 K superconductor LaFePO. In the process, scanning SQUID susceptometry is demonstrated as a technique for accurately measuring local temperature-dependent changes in lambda, ideal for studying early or difficult-to-grow m...

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Bibliographic Details
Published in:Physical review letters 2009-09, Vol.103 (12), p.127003-127003, Article 127003
Main Authors: Hicks, Clifford W, Lippman, Thomas M, Huber, Martin E, Analytis, James G, Chu, Jiun-Haw, Erickson, Ann S, Fisher, Ian R, Moler, Kathryn A
Format: Article
Language:English
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Summary:We measure changes in the penetration depth lambda of the T_{c} approximately 6 K superconductor LaFePO. In the process, scanning SQUID susceptometry is demonstrated as a technique for accurately measuring local temperature-dependent changes in lambda, ideal for studying early or difficult-to-grow materials. lambda is found to vary linearly with temperatures from 0.36 to approximately 2 K, with a slope of 143 +/- 15 A/K, suggesting line nodes in the superconducting order parameter. The linear dependence up to approximately T_{c}/3, similar to the cuprate superconductors, indicates well-developed nodes.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.103.127003