  The observation of spin-dependent transmission of electrons through chiral
molecules has led to the discovery of chiral-induced spin selectivity (CISS).
The remarkably high efficiency of the spin polarizing effect has recently
gained significant interest due to the high potential for novel sustainable
hybrid chiral molecule magnetic applications. However, the fundamental
mechanisms underlying the chiral-induced phenomena remain to be understood
fully. In this work, we explore the impact of chirality on spin angular
momentum in hybrid metal/ chiral molecule thin film heterostructures. For this,
we inject a pure spin current via spin pumping and investigate the
spin-to-charge conversion at the hybrid chiral interface. Notably, we observe a
chiral-induced unidirectionality in the conversion. Furthermore,
angle-dependent measurements reveal that the spin selectivity is maximum when
the spin angular momentum is aligned with the molecular chiral axis. Our
findings validate the central role of spin angular momentum for the CISS
effect, paving the path toward three-dimensional functionalization of hybrid
molecule-metal devices via chirality.
