AVS 52nd International Symposium
    Magnetic Interfaces and Nanostructures Tuesday Sessions
       Session MI+NS-TuM

Paper MI+NS-TuM2
Core Size Effects on Core-Shell Structured Fe/FeO@sub x@ Nanopaticles

Tuesday, November 1, 2005, 8:40 am, Room 204

Session: Magnetic Nanostructures, Surfaces, and Interfaces
Presenter: A. Ceylan, University of Delaware
Authors: A. Ceylan, University of Delaware
S. Shah, University of Delaware
K. Hasanain, Quaid-e-Azam University, Pakistan
Correspondent: Click to Email
In this study, we examined the particle size dependence of magnetic properties of Fe/Fe-oxide core/shell structured nanoparticles. Inert gas condensation has been used to synthesize the nanoparticles. Structural and magnetic properties of the samples have been investigated by various techniques. It has been observed that the effect of AFM shell can be relatively enhanced by decreasing the core size such that much higher exchange bias than larger particles is obtained. Furthermore, as an indication of pinned spins, which are attributed as one of the reasons of higher exchange bias field, at the AFM-FM interface, a vertical shift at the hysteresis loops has also been observed in small nanoparticles. Room temperature magnetic measurements have revealed that small particles show superparamagnetic behavior. However, the system does not reach to saturation even at 4T which indicates high anisotropy. These observations reveal that superparamagnetic behavior is related to the small size rather than a lack of anisotropy.