  Two dimensional (2D) superconducting systems are of great importance to
exploring exotic quantum physics. Recent development of fabrication techniques
stimulates the studies of high quality single crystalline 2D superconductors,
where intrinsic properties give rise to unprecedented physical phenomena. Here
we report the observation of Zeeman-type spin-orbit interaction protected
superconductivity (Zeeman-protected superconductivity) in 4 monolayer (ML) to 6
ML crystalline Pb films grown on striped incommensurate (SIC) Pb layers on
Si(111) substrates by molecular beam epitaxy (MBE). Anomalous large in-plane
critical field far beyond the Pauli limit is detected, which can be attributed
to the Zeeman-protected superconductivity due to the in-plane inversion
symmetry breaking at the interface. Our work demonstrates that in
superconducting heterostructures the interface can induce Zeeman-type
spin-orbit interaction (SOI) and modulate the superconductivity.
