  When an electron passes through a chiral molecule there is a high probability
for a correlation between the momentum and spin of the charge, thus leading to
spin polarized current. This phenomenon is known as the chiral induced spin
selectivity (CISS) effect. One of the most surprising experimental results
recently demonstrated is that magnetization reversal in a ferromagnet (FM) with
perpendicular anisotropy can be realized solely by chemisorbing a chiral
molecular monolayer without applying any current or external magnetic field.
This result raises the currently open question of whether this effect is due to
the bonding event, held by the ferromagnet, or a long timescale effect
stabilized by exchange interactions. In this work we have performed vectorial
magnetic field measurements of the magnetization reorientation of a
ferromagnetic layer exhibiting perpendicular anisotropy due to CISS using
nitrogen-vacancy centers in diamond, and followed the time dynamics of this
effect. In parallel, we have measured the molecular monolayer tilt angle in
order to find a correlation between the time dependence of the magnetization
re-orientation and the change of the tilt angle of the molecular monolayer. We
have identified that changes in the magnetization direction correspond to
changes of the molecular monolayer tilt angle, providing evidence for a
long-timescale characteristic of the induced magnetization reorientation. This
suggests that the CISS effect has an effect over long-timescales which we
attribute to exchange interactions. These results offer significant insights
into the fundamental processes underlying the CISS effect, contributing to the
implementation of CISS in state-of-the-art applications such as spintronic and
magnetic memory devices.
