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arXiv · 0903.5260

Evidence for Nodal Superconductivity in LaFePO from Scanning SQUID Susceptometry

Clifford W. Hicks·Thomas M. Lippman·Martin E. Huber·James G. Analytis·Jiun-Haw Chu·Ann S. Erickson·Ian R. Fisher·Kathryn A. Moler
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Abstract

We measure changes in the penetration depth $\lambda$ of the $T_c \approx 6$ K superconductor LaFePO. In the process scanning SQUID susceptometry is demonstrated as a technique for accurately measuring {\it local} temperature-dependent changes in $\lambda$, making it ideal for studying early or difficult-to-grow materials. $\lambda$ of LaFePO is found to vary linearly with temperature from 0.36 to $\sim$2 K, with a slope of 143$\pm$15 \AA/K, suggesting line nodes in the superconducting order parameter. The linear dependence up to $\sim T_c/3$ is similar to the cuprate superconductors, indicating well-developed nodes.

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Clifford W. Hicks, Thomas M. Lippman, Martin E. Huber, James G. Analytis, Jiun-Haw Chu, Ann S. Erickson, Ian R. Fisher, Kathryn A. Moler. 2009-03-30. Evidence for Nodal Superconductivity in LaFePO from Scanning SQUID Susceptometry. https://doi.org/10.1103/physrevlett.103.127003

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