  Artificial active particles, exemplified by Hexbugs (HB), serve as valuable
tools for investigating the intricate dynamics of active matter systems.
Leveraging their stochastic motion, Hexbugs provides an excellent experimental
model. In this study, we utilize Hexbugs equipped with disk-like armor and
embedded magnetic dipoles, transforming them into Magnetic Self-Propelled
Particles (MSPP). We explore the emergence of collective and stationary states
numerically and experimentally by confining these MSPPs within a parabolic
domain acting as a harmonic potential. Our findings unveil a diverse range of
metastable configurations intricately linked to the complex dynamics inherent
in the system. We discern that particle number, activity, and the balance
between magnetic and harmonic potential strengths predominantly influence the
metastability of these structures. By employing these parameters as control
factors, we compare and contrast the behavior of MSPPs with disk-like magnetic
Active Brownian Particles (ABPs) in the overdamped limit of vanishing inertia.
Our numerical predictions reproduce most of the experimental observations,
highlighting the crucial role of magnetic dipole interactions in developing
novel configurations for active particles within parabolic domains. These
configurations include chains, clusters, and vortex formations characterized by
a specific pattern in the particle spatial distribution. Notably, we observe
that the influence of inertia is not fundamental in generating metastable
configurations in these confined systems. Instead, the particle's shape,
activity, and orientation are dominant factors. This comparative analysis
provides insights into the distinctive features and dynamics of MSPP within
confined environments, shedding light on the role of short-range polar
interactions.
