This U.S.-Brazil Cooperative Science award will support the collaboration of Yaacov Shapira of Tufts University and N.F. Oliveira, Jr. and V. Bindilatti of the University of Sao Paulo (USP), Brazil. The project aims to focus on magnetic interactions in dilute magnetic semiconductors. These materials are ideal for exploring the fundamental properties of these interactions. The researchers' joint experiments will take advantage of the very low temperatures which are being produced at USP using a new class of plastic dilution refrigerators. The experiments at very high magnetic fields will be conducted in U.S. high-magnetic-field facilities with which the Tufts group is affiliated. The goal of these experiments will be to answer various basic questions, including how the magnetic interactions fall off with distance. The U.S. side will benefit from access to USP's new plastic dilution refrigerators and superconducting magnets. The Brazilian side will acquire expertise in the use of magnetization steps to determine exchange constants, as well as sources for the single crystals to be used in these experiments.
