  We performed 121/123Sb-nuclear quadrupole resonance (NQR) measurements on the
superconducting (SC) line-nodal material CaSb2 in order to investigate
electronic properties in the normal and SC states from a microscopic point of
view. In the normal state, the nuclear spin-lattice relaxation rate 1/T1 for
the Sb(1) site, which is responsible for the line-nodal parts, is approximately
proportional to temperature, indicating the conventional Fermi liquid state.
From comparison with band structure calculations, it is considered that the NQR
properties related to the line-nodal character are hidden because the
conventional behavior originating from Fermi-surface parts away from the nodes
is dominant. In the SC state, a clear coherence peak just below the transition
temperature and an exponential decrease at lower temperatures were observed in
1/T1. These results strongly suggest that conventional s-wave superconductivity
with a full gap is realized in CaSb2.
