  Kramers nodal lines (KNLs) have recently been proposed theoretically as a
special type of Weyl line degeneracy connecting time-reversal invariant
momenta. KNLs are robust to spin orbit coupling and are inherent to all
non-centrosymmetric achiral crystal structures, leading to unusual spin,
magneto-electric, and optical properties. However, their existence in in real
quantum materials has not been experimentally established. Here we gather the
experimental evidence pointing at the presence of KNLs in SmAlSi, a
non-centrosymmetric metal that develops incommensurate spin density wave order
at low temperature. Using angle-resolved photoemission spectroscopy, density
functional theory calculations, and magneto-transport methods, we provide
evidence suggesting the presence of KNLs, together with observing Weyl fermions
under the broken inversion symmetry in the paramagnetic phase of SmAlSi. We
discuss the nesting possibilities regarding the emergent magnetic orders in
SmAlSi. Our results provide a solid basis of experimental observations for
exploring correlated topology in SmAlSi.
