  Ultrafast manipulations of magnetic phases are eliciting increasing attention
from the scientific community, because potentially relevant to the
understanding of nonequilibrium phase transitions and to novel technologies.
Here, we focus on manipulations applied to magnetic impurities in metallic
hosts. By considering small nanoring geometries, we show how currents can
induce a dynamical switching between different types of exchange interactions
in these systems. Our work thus opens a study window on nonequilibrium
Doniach's magnetic phase diagrams, and time-dependent Kondo-vs-RKKY scenarios.
