Characterisation of magnetic nanoparticles by temperature dependent measurement of magnetic relaxation

The utilisation of magnetorelaxometry using labels containing magnetic nanoparticles (MNP) establishes new fields of application in medical in vitro and in vivo diagnostics [1]. An essential prerequisite for the implementation of these diagnostic procedures consists in a noticable improvement of the sensitivity by development of MNP providing a large relaxation signal. We present a new method for the characterisation of MNP based on the analysis of the Néel relaxation signal subjected to the temperature of the sample. In contrast to the established characterisation methods, the new method directly leeds to the energy barrier distribution of the particles. Hence, the rate of particles contributing to the signal can be distinguished and specifically affected in the preparation process.