  We report on muon spin rotation (muSR) studies of the superconducting and
magnetic properties of the ternary intermetallic stannide Ca3Ir4Sn13. 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
muSR time scale. The field-induced magnetization cannot be attributed to
localized magnetic moments. In particular, our muSR data reveal that the
anomaly observed in thermal and transport properties at T*~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 lambda=385(1) nm
and the electron-phonon pairing interaction is in the strong-coupling limit.
