  The ubiquitous domain wall kinetics under magnetic field or current
application describes the dynamic properties in nanostructured magnets.
However, when the geometrical size of a nanomagnetic system is constricted to
the limiting domain wall length scale, the competing energetics between
anisotropy, exchange and dipolar interactions can cause emergent kinetics due
to quasiparticle relaxation, similar to bulk magnets of atomic origin. Here, we
present a joint experimental and theoretical study to support this argument --
constricted nanomagnets, made of antiferromagnetic and paramagnetic neodymium
thin film with honeycomb motif, reveal fast kinetic events at ps time scales
due to the relaxation of chiral vortex loop-shaped topological quasiparticles
that persist to low temperature in the absence of any external stimuli. Such
phenomena are typically found in macroscopic magnetic materials. Our discovery
is especially important considering the fact that paramagnets or
antiferromagnets have no net magnetization. Yet, the kinetics in neodymium
nanostructures is quantitatively similar to that found in ferromagnetic
counterparts and only varies with the thickness of the specimen. This suggests
that a universal, topological quasiparticle mediated dynamical behavior can be
prevalent in nanoscopic magnets, irrespective of the nature of underlying
magnetic material.
