Non-Locality and Strong Coupling in the Heavy Fermion Superconductor CeCoIn$_{5}$: A Penetration Depth Study

• Main Authors: Chia, Elbert E. M, Van Harlingen, D. J, Salamon, M. B, Yanoff, Brian D, Bonalde, I, Sarrao, J. L
• Format: Journal Article
• Language: English
• Published: 24-06-2002
• Subjects: Physics - Superconductivity
• DOI: 10.48550/arxiv.cond-mat/0206468

Phys. Rev. B, Vol. 67, 014527 (2003) We report measurements of the magnetic penetration depth $\lambda$ in single
crystals of CeCoIn$_{5}$ down to $\sim$0.14 K using a tunnel-diode based,
self-inductive technique at 28 MHz. While the in-plane penetration depth tends
to follow a power law, $\lambda_{//} \sim {\it T}^{3/2}$, the data are better
described as a crossover between linear ({\it T} $\gg $ ${\it T}^\ast $) and
quadratic ({\it T} $\ll {\it T}^\ast $) behavior, with ${\it T}^\ast $ the
crossover temperature in the strong-coupling limit. The {\it c}-axis
penetration depth $\lambda_{\perp} $ is linear in {\it T}, providing evidence
that CeCoIn$_{5}$ is a {\it d}-wave superconductor with line nodes along the
{\it c}-axis. The different temperature dependences of $\lambda_{//} $ and
$\lambda_{\perp} $ rule out impurity effects as the source of ${\it T}^{\ast}
$.