Type: Article
Publication Date: 2013-09-04
Citations: 32
DOI: https://doi.org/10.1103/physrevb.88.104505
We report on muon spin rotation ($\ensuremath{\mu}$SR) studies of the superconducting and magnetic properties of the ternary intermetallic stannide Ca${}_{3}$Ir${}_{4}$Sn${}_{13}$. This material has recently been the focus of intense research activity due to a proposed interplay of ferromagnetic spin fluctuations and superconductivity. In the temperature range $T=1.6$--200 K, we find that the zero-field muon relaxation rate is very low and does not provide evidence for spin fluctuations on the $\ensuremath{\mu}$SR time scale. The field-induced magnetization cannot be attributed to localized magnetic moments. In particular, our $\ensuremath{\mu}$SR data reveal that the anomaly observed in thermal and transport properties at ${T}^{*}\ensuremath{\approx}38$ K is not of magnetic origin. Results for the transverse-field muon relaxation rate at $T=0.02$--12 K suggest that superconductivity emerges out of a normal state that is not of a Fermi-liquid type. This is unusual for an electronic system lacking partially filled $f$-electron shells. The superconducting state is dominated by a nodeless order parameter with a London penetration depth of ${\ensuremath{\lambda}}_{\mathrm{L}}=385(1)$ nm and the electron-phonon pairing interaction is in the strong-coupling limit.