We study an unique form of metallic ferromagnetism in which orbital moments
surpasses the role of spin moments in shaping the overall magnetization. This
system emerges naturally upon doping a topologically non-trivial Chern band in
the recently identified quarter metal phase of rhombohedral trilayer graphene.
Our comprehensive scan of the density-interlayer potential parameter space
reveals an unexpected landscape of orbital magnetization marked by two sign
changes and a line of singularities. The sign change originates from an intense
Berry curvature concentrated close to the band-edge, and the singularity arises
from a topological Lifshitz transition that transform a simply connected Fermi
sea into an annular Fermi sea. Importantly, these variations occur while the
groundstate order-parameter (i.e.~valley and spin polarization) remains
unchanged. This unconventional relationship between the order parameter and
magnetization markedly contrasts traditional spin ferromagnets, where spin
magnetization is simply proportional to the groundstate spin polarization via
the gyromagnetic ratio. We compute energy and magnetization curves as functions
of collective valley rotation to shed light on magnetization dynamics and to
expand the Stoner-Wohlfarth magnetization reversal model. We provide
predictions on the magnetic coercive field that can be readily tested in
experiments. Our results challenge established perceptions of magnetism,
emphasising the important role of orbital moments in two-dimensional materials
such as graphene and transition metal dichalcogenides, and in turn, expand our
understanding and potential manipulation of magnetic behaviors in these
systems.Comment: 4+8 page