  We investigated spin injection by spin pumping from a spin-injector(NiFe)
into a spin-sink to detect spin fluctuations in the spin-sink. By scanning the
ordering-temperature of several magnetic transitions, we found that enhanced
spin pumping due to spin fluctuations applies with several ordering states:
ferromagnetic(Tb) and antiferromagnetic(NiO, NiFeOx, BiFeO3, exchange-biased
and unbiased IrMn). Results also represent systematic experimental
investigation supporting that the effect is independent of the metallic and
insulating nature of the spin-sink, and is observed whether the spin current
probe involves electronic or magnonic transport, facilitating advances in
material characterization and engineering for spintronic applications.
