  Magnetic moments dilutely dispersed in a metallic host tend to be coupled
through the conduction electrons of the metal. This indirect exchange coupling,
known to occur for a variety of magnetic materials embedded in several
different metallic structures, is of rather long range, especially for
low-dimensional structures like carbon nanotubes. Motivated by recent claims
that the indirect coupling between magnetic moments in precessional motion has
a much longer range than its static counterpart, here we consider how magnetic
atoms adsorbed to the walls of a metallic nanotube respond to a time-dependent
perturbation that induces their magnetic moments to precess. By calculating the
frequency-dependent spin susceptibility we are able to identify resonant peaks
whose respective widths provide information about the dynamic aspect of the
indirect exchange coupling. We show that by departing from a purely static
representation to another in which the moments are allowed to precess, we
change from what is already considered a long range interaction to another
whose range is far superior. In other words, localized magnetic moments
embedded in a metallic structure can feel each other's presence more easily
when they are set in precessional motion. We argue that such an effect can have
useful applications leading to large-scale spintronics devices.
