0305360

1. Enhanced Ferromagnetismof Nanolayer (Co,Mn) Alloys on GaAsDon Heiman, Northeastern University, DMR-0305360 An emerging topic in this field is the prospect of altering or tailoring the properties of nanometer thick layers by forcing them into nonequilibrium crystal structures, or by inducing a residual strain. We have found that epitaxial nanometer thick layers of Co1-xMnx alloys grown on GaAs exhibit enhanced magnetic properties. These nanolayers are ferromagnetic for Mn concentrations up to x=0.8, a much larger dilution than observed for bulk-grown alloys. The ferromagnetic Curie temperature, TC(x), is found to be above room temperature for x<0.6. This type of strain-induced ferromagnetism could have an advantage in a semiconductor/ferromagnet heterostructure device. An important goal of materials research and device engineering has been to discover new methods for combining ferromagnets with semiconductors. Although information technology relies on either semiconductors OR ferromagnets, the search continues for device structures which combine these materials. With this goal in mind, one avenue of research is the search for ferromagnetic materials which are compatible with Si and GaAs semiconductors.

2. Enhanced Ferromagnetismof Nanolayer (Co,Mn) Alloys on GaAsDon Heiman, Northeastern University, DMR-0305360 An important goal of this research is to foster cross-departmental education and training in nanoscience, as well as the introduction of an industrial component. The collaborators of this work included: physics and engineering students from Northeastern University and Boston University; and a scientist from Quantum Design, Inc. In addition, undergraduate students were involved in several aspects of the work. These opportunities could inspire individuals to develop into research leaders for the 21st, whose work is aimed at important problems such as developing advanced electronic devices.