  In this work we investigate the ground state of a momentum-confined
interacting 2D electron gas, a momentum-space analog of an infinite quantum
well. The study is performed by combining analytical results with a numerical
exact diagonalization procedure. We find a ferromagnetic ground state near a
particular electron density and for a range of effective electron (or hole)
masses. We argue that this observation may be relevant to the generalized
Stoner ferromagnetism recently observed in multilayer graphene systems. The
collective magnon excitations exhibit a linear dispersion, which originates
from a diverging spin stiffness.
