To elucidate magnetic excitations in diluted Ising magnets over the entire magnetic concentration, we performed neutron inelastic-scattering experiments on two-dimensional diluted Ising magnets ${\mathrm{Rb}}_2$${\mathrm{Co}}_{\mathit{c}}$${\mathrm{Mg}}_{1\mathrm{-}\mathit{c}}$${\mathrm{F}}_4$, (c=0.1,0.2,0.3,0.4,0.5,0.58), whose magnetic concentration was below the percolation threshold. We found that Ising cluster excitations and intracluster excitations coexist over the entire concentration region, and that the scattering intensities from these different origins change with the concentration.

• Received 12 July 1991

DOI:https://doi.org/10.1103/PhysRevB.45.7484