  Topologically protected swirl of the magnetic texture known as the Skyrmion
has become ubiqui- tous in both metallic and insulating chiral magnets.
Meanwhile the existence of its three-dimensional analogue, known as the
magnetic monopole, has been suggested by various indirect experimental sig-
natures in MnGe compound. Theoretically, Ginzburg-Landau arguments in favor of
the formation of a three-dimensional crystal of monopoles and anti-monopoles
have been put forward, however no microscopic model Hamiltonian was shown to
support such a phase. Here we present strong numerical evidence from Monte
Carlo simulations for the formation of a rock-salt crystal structure of
monopoles and anti-monopoles in short-period chiral magnets. Real-time
simulation of the spin dynamics suggests there is only one collective mode in
the monopole crystal state in the frequency range of several GHz for the
material parameters of MnGe.
