At nanometer dimensions, magnetic excitation bands transform into discrete eigenmodes
with nontrivial shape and size dependence. The eigenmode spectral peak positions are well-
understood in terms of conventional micromagnetics [RD McMichael and MD Stiles, J. Appl.
Phys. 97, 10J901 (2005)][HT Nembach, et al., Phys. Rev. B 83, 094427 (2011)]. However,
the effect of finite size on the damping process is not yet settled. Conventional
micromagnetics does not predict any effect, insofar as numerical formulations of …

We demonstrate a strong dependence of the effective damping on the nanomagnet size and
the particular spin-wave mode that can be explained by the theory of intralayer transverse-
spin pumping. The effective Landau-Lifshitz damping is measured optically in individual,
isolated nanomagnets as small as 100 nm. The measurements are accomplished by use of
a novel heterodyne magneto-optical microwave microscope with unprecedented sensitivity.
Experimental data reveal multiple standing spin-wave modes that we identify by use of …