  Spontaneous symmetry breaking is central to the description of interacting
phases of matter. Here we reveal a new mechanism through which a driven
interacting system subject to a time-reversal symmetric driving field can
spontaneously magnetize. We show that the strong internal ac fields of a metal
driven close to its plasmon resonance may enable Berryogenesis: the spontaneous
generation of a self-induced Bloch band Berry flux. The self-induced Berry flux
supports and is sustained by a circulating plasmonic motion, which may arise
even for a linearly polarized driving field. This non-equilibrium phase
transition occurs above a critical driving amplitude, and may be of either
continuous or discontinuous type. Berryogenesis relies on feedback due to
interband coherences induced by internal fields, and may readily occur in a
wide variety of multiband systems. We anticipate that graphene devices, in
particular, provide a natural platform to achieve Berryogenesis and
plasmon-mediated spontaneous non-equilibrium magnetization in present-day
devices.
