Superradiant Operation of Spin Masers
  The theory of spin superradiance, developed earlier for nuclear magnets, is generalized to a wider class of spin systems, such as granular magnets and molecular magnets. The latter may possess strong single-site magnetocrystalline anisotropy, whose role in nonlinear spin dynamics is analysed. Transient as well as pulsing superradiant regimes are described. These coherent regimes may be employed in the operation of spin masers. 
V. I. Yukalov