  We report a highly unusual angular variation of the upper critical field
(H_c2) in epitaxial superlattices CeCoIn_5(n)/YbCoIn_5(5), formed by
alternating layers of n and a 5 unit-cell thick heavy-fermion superconductor
CeCoIn_5 with a strong Pauli effect and normal metal YbCoIn_5, respectively.
For the n=3 superlattice, H_{c2}(\theta) changes smoothly as a function of the
field angle \theta. However, close to the superconducting transition
temperature, H_{c2}(\theta) exhibits a cusp near the parallel field (\theta=0
deg). This cusp behavior disappears for n=4 and 5 superlattices. This sudden
disappearance suggests the relative dominance of the orbital depairing effect
in the n=3 superlattice, which may be due to the suppression of the Pauli
effect in a system with local inversion symmetry breaking. Taking into account
the temperature dependence of H_{c2}(\theta) as well, our results suggest that
some exotic superconducting states, including a helical superconducting state,
might be realized at high magnetic fields.
