"Magnetic nanoparticles have a number of present and proposed applications in biology and medicine, such as bio-separation, drug delivery, magnetic resonance imaging and hyperthermia cancer treatment, as well as important role in future high density data storage and spintronic devices. Therefore, there is high interest and strong need to characterize them properly. So far the common characterization method has been to measure a large number of them together in order to accumulate sufficient signal. This is problematic because the magnetic properties of nanomagnets are inherently sensitive to small variations in volume, shape and structure, and this strong variability is averaged in the bulk. It is therefore vital to characterize nanomagnets individually. Successful experiments are rare and required extensive efforts to characterize one single particle. I propose to use a scanning SQUID with sufficient sensitivity and spatial resolution to detect an individual nanomagnet and use the scanning capability to sample many individuals to gain statistics about the variability of their physical properties. In addition to establishing a breakthrough characterization tool, I plan to address physical questions of interest such as the nature of the interactions between small numbers of particles, the dynamics of these particles and the distribution of physical properties. To accomplish this we need an extremely high moment sensitivity, sufficient spatial resolution, minimal magnetic influence of the probe on the particle, and access to various temperatures. These requirements point to the SQUID as an ideal candidate for this task. In the framework of this grant I plan to investigate two types of nanomagnets: FePt particles, which are candidates for biomedical applications; and CoFe dots fabricated on multiferroic materials for electric-field control of local ferromagnetism. The latter is of high interest for memory and logic device applications."