Abstract
We report measurements of the magnetic penetration depth in single crystals of down to 0.1 K, with the ac field applied along the , , and directions. In all three field orientations, and superfluid density for . Data are best fit by the A-phase-like gap with multidomains, each having two point nodes along a cube axis, and parameter , suggesting that is a strong-coupling superconductor with two point nodes on the Fermi surface. We also confirm the double transitions at 1.75 and 1.85 K seen in other measurements.
- Received 22 August 2003
DOI:https://doi.org/10.1103/PhysRevLett.91.247003
©2003 American Physical Society