This article is focused on the dynamics of a rotating electrically conducting
fluid in a turbulent state. As inside the Earth's core or in various industrial
processes, a flow is altered by the presence of both background rotation and a
large scale magnetic field. In this context, we present a set of 3D direct
numerical simulations of incompressible decaying turbulence. We focus on
parameters similar to the ones encountered in geophysical and astrophysical
flows, so that the Rossby number is small, the interaction parameter is large,
but the Elsasser number, defining the ratio between Coriolis and Lorentz
forces, is about unity. These simulations allow to quantify the effect of
rotation and thus inertial waves on the growth of magnetic fluctuations due to
Alfv\'en waves. Rotation prevents the occurrence of equipartition between
kinetic and magnetic energies, with a reduction of magnetic energy at
decreasing Elsasser number {\Lambda}. It also causes a decrease of energy
transfer mediated by cubic correlations. In terms of flow structure, a decrease
of {\Lambda} corresponds to an increase in the misalignment of velocity and
magnetic field.Comment: 18 pages, 12 figure
