Muon spin relaxation study of spin dynamics in a polysaccharide iron complex.

Polysaccharide iron complex, a ferritin analog, has been examined with zero-field muon spin-relaxation at temperatures from 2 to 40 K. Spectra exhibit a clear separation of static moments and collective excitations at low temperatures. At intermediate temperatures, superparamagnetic relaxation is observed and a blocking temperature of T[sub B]=10±2.5 K is measured, in agreement with transmission Mo¨ssbauer spectra and frequency dependent χ[sub ac] data. Superparamagnetic relaxation rates of 20-150 MHz are in agreement with those extrapolated from Mo¨ssbauer spectra using a multilevel magnetic relaxation model. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]