  Nodal semimetals are a unique platform to explore topological signatures of
the unusual band structure that can manifest by accumulating a nontrivial phase
in quantum oscillations. Here we report a study of the de Haasvan Alphen
oscillations of the candidate topological nodal line semimetal CaAgAs using
torque measurements in magnetic fields up to 45 T. Our results are compared
with calculations for a toroidal Fermi surface originating from the nodal ring.
We find evidence of a nontrivial Berry phase shift only in one of the
oscillatory frequencies. We interpret this as a Berry phase arising from the
semi-classical electronic Landau orbit which links with the nodal ring when the
magnetic field lies in the mirror (ab) plane. Furthermore, additional Berry
phase accumulates while rotating the magnetic field for the second orbit in the
same orientation which does not link with the nodal ring. These effects are
expected in CaAgAs due to the lack of inversion symmetry. Our study
experimentally demonstrates that CaAgAs is an ideal platform for exploring the
physics of nodal line semimetals and our approach can be extended to other
materials in which trivial and nontrivial oscillations are present.
