  Spin-transfer and spin-orbit torques allow controlling magnetic degrees of
freedom in various materials and devices. However, while the transfer of
angular momenta between electrons has been widely studied, the contribution of
nuclear spins has yet to be explored further. This article demonstrates that
the hyperfine coupling, which consists of Fermi contact and dipolar
interactions, can mediate the application of spin-orbit torques acting on
nuclear spins. Our starting point is a sizable nuclear spin in a metal with
electronic spin accumulation. Then, via the hyperfine interactions, the nuclear
spin modifies the an electronic spin density. The reactions to the equilibrium
and nonequilibrium components of the spin density is a torque on the nucleus
with field-like and damping-like components, respectively. This nuclear
spin-orbit torque is a step toward stabilizing and controlling nuclear magnetic
momenta, in magnitude and direction, and realizing nuclear spintronics.
