  The magnetic correlations at the superconductor/ferromagnet (S/F) interfaces
play a crucial role in realizing dissipation-less spin-based logic and memory
technologies, such as triplet-supercurrent spin-valves and "{\pi}" Josephson
junctions. Here we report the coexistence of an induced large magnetic moment
and a crypto ferromagnetic state at high-quality nitride S/F interfaces. Using
polarized neutron reflectometry and d. c. SQUID measurements, we quantitatively
determined the magnetization profile of S/F bilayer and confirmed the induced
magnetic moment in the adjacent superconductor only exists below TC.
Interestingly, the direction of the induced moment in the superconductors was
unexpectedly parallel to that in the ferromagnet, which contrasts with earlier
findings in S/F heterostructures based on metals or oxides. The
first-principles calculations verify the observed unusual interfacial spin
texture is caused by the Heisenberg direct exchange coupling through d orbital
overlapping and severe charge transfer across the interfaces. Our work
establishes an incisive experimental probe for understanding the magnetic
proximity behavior at S/F interfaces and provides a prototype epitaxial
building block for superconducting spintronics.
