9803218 Furdyna This renewal proposal by Profs. J. Furdyna (University of Notre Dame), J.J. Rhyne (University of Missouri/Columbia), with Prof. C.M. Sorensen (Kansas State University) as a sub-contractor describes research using neutron scattering experiments to study semiconductor thin films and nanostructures in order to gain an understanding of magnetic ordering and magnetic interactions in such systems. The proposed research is composed of three interrelated areas: the identification of mechanisms which determine interlayer coupling in MnSe- and MnTe-based superlattices, systematic investigations to enable distinguishing between the effects of strain and those of dilution on the antiferromagnetic transitions in Mn(1-x)IIxIV alloys, and a new exploratory investigation of spin ordering and exchange interactions in magnetic semiconductor nano-particles. Specific thin film systems are MnTe/Zn(1-x)MnxTe superlattices and Mn(1- x)MgxTe with varying doping values of x. Also to be studied are the magnetic properties of Mn nanocrystals. %%% The objective of this research is to apply neutron scattering techniques to magnetic semiconductor thin films and nanostructures in order to gain understanding of magnetic ordering and magnetic interactions in these systems. Magnetic semiconductors are of great fundamental interest in magnetism, because their manganese sublattices constitute frustrated Heisenberg antiferromagnets governed by short-range interactions. Three areas of investigation are proposed. First, magnetic/non-magnetic superlattices , such as manganese-tellurium/zinc-tellurium will be studied in order to elucidate the mechanisms responsible for the coupling between magnetic layers for magnetic interactions. In the second part the investigators will exploit newly developed techniques for growing materials composed of group II and group VI elements (II-VI all oys), specifically with the group IIa elements magnesium and berillium, in order to elucidate the effect of dilution and strain on the antiferromagnetic transition in diluted magnetic alloys. In the third part an exploratory pilot program will be started that focuses on neutron scattering in II-VI-based nanoparticles containing high concentrations of manganese. These studies will be performed in a collaboration between the principal investigator Prof. Furdyna (University of Notre Dame), the co-principal investigator Prof. J.J. Rhyne (University of Missouri - Columbia), and the sub-contractor Prof. C.M. Sorensen of the Kansas State University. The researches promise to contribute greatly to the understanding of magnetic interactions and thereby assist in the development of new and improved practical devices. ***
