Magnetic characterization of cobalt nanoparticles by temperature‐dependent magnetic relaxation measurements

Abstract

Abstract A recently introduced method for the characterization of magnetic nanoparticles based on the analysis of the dependence of the Néel relaxation signal on the sample temperature (temperature‐dependent magnetorelaxometry, TMRX) has been applied to characterize air‐stable cobalt particles made by decomposition of Co 2 (CO) 8 in the presence of aluminium‐organic compounds. The influence of small changes in the preparation process on the magnetic relaxation behaviour has been studied. A mean magnetically relevant particle size has been derived from TMRX, zero‐field cooled magnetisation and low‐temperature coercivity measurements and has been compared with a mean physical size determined by transmission electron microscopy investigations. Copyright © 2004 John Wiley & Sons, Ltd.