  For viable applications, spintronic devices based e.g. on domain wall motion
need to be highly reliable with stable magnetization states and highly
reproducible switching pathways transforming one state to another. The
existence of multiple stable states and switching pathways in a system is a
definitive barrier for device operation, yet rare and stochastic events are
difficult to detect and understand. We demonstrate an approach to quantify
competing magnetic states and stochastic switching pathways based on
time-resolved scanning electron microscopy with polarization analysis, applied
to the technologically relevant control of vortex domain wall chirality via
field and curvature in curved wires. While being a pump-probe technique, our
analysis scheme nonetheless allows for the disentanglement of different
occurring dynamic pathways and we can even identify the rare events leading to
changes from one magnetization switching pathway to another pathway via
temperature- and geometry-dependent measurements. The experimental imaging is
supported by micromagnetic simulations to reveal the mechanisms responsible for
the change of the pathway. Together the results allow us to explain the origin
and details of the domain wall chirality control and to quantify the frequency
and the associated energy barriers of thermally activated changes of the states
and switching pathways.
