1999 Summer Native American Undergraduate Research Fellow

Back to 1999 Archives

April Rogoyski

April is a freshman studying Physics at the University of Minnesota

Frontiers of AFM and MFM
April Rogoyski
University of Minnesota

E. Dan Dahlberg
Department Physics, University of Minnesota

In studies of the coupling between ferromagnets and antiferromagnets (F/AF), most experiments measure some physical property of the F/AF coupling energy without knowledge of the location in the sample being probed, i.e., most studies use bulk probes which measure a signal from the entire sample such as vibrating sample magnetometer magnetization measurements. Although this certainly provides information on the F/AF coupling, it now appears that for a complete understanding of the phenomena, spatially localized studies must be made. For example, the field training effects which occur when the magnetization of the ferromagnet is reversed is most likely associated with either some type of irreversible domain wall in the ferromagnet or antiferromagnet or a rotation of both magnetization sublattices in smaller antiferromagnetic crystallites. In order to study the spatial variations in the F/AF coupling, we have begun magnetic force microscopy studies with in situ magnetic fields of the magnetic reversal in F/AF bilayers. These studies will allow us to determine nucleation sites of t he magnetization reversal and compare the domain structure in the ferromagnet upon repeated cycles of the reversal. This type of investigation will provide a microscopic picture of the coupling and how the grain size of the antiferromagnet controls the process. Most of the effort to date has been to develop a proficiency in scanning probe microscopy.