Apparent magnetic energy-barrier distribution in FePt nanoparticles

Zero-field magnetic viscosity measurements at temperatures between 2 and 30 K were made on a sample of chemically disordered FePt nanoparticles prepared by solution phase chemical synthesis. The data have been used to calculate the apparent magnetic-moment-weighted energy barrier distribution for the FePt. This distribution is composed of a log-normal distribution plus a second distribution that is well described by an exponential decay of barrier frequency with increasing barrier height. The two distributions contribute approximately equally to the overall distribution.