In recent years, new advanced materials have usually been discovered through the substitution or altering of the ratio of atoms in a known compound (sometimes based on the predictions of computer models). With combinatorial synthesis, in which thousands of distinct combinations of molecules are deposited onto a square grid the size of a checkerboard square, scientists can look at many atom substitutions and ratio adjustments in a single combinatorial library. To look for new materials with magnetoresistance, Berkeley Lab scientists started with a well-studied class of MR materials based on manganese oxide, substituted similar elements from the periodic table (iron, vanadium and cobalt) for manganese, and made a separate combinatorial library for each one. Their cobalt oxide library yielded 26 new materials that displayed magnetoresistance comparable to the so-called "colossal" class of magnetoresistance materials.
Because colossal magnetoresistant materials (CMR) become superconducting in the presence of a sufficiently strong magnetic field, thin films of these materials are in great demand by the electronics industry. Currently, these materials are limited to laboratory studies, where they are made through a costly technique called pulsed laser ablation. The situation may soon change, however. Berkeley Lab scientists at NCEM this past year unveiled a relatively inexpensive chemical process for making CMR thin films out of the same class of ceramic materials that exhibit high-temperature superconductivity. At a fraction of the cost of pulsed laser ablation, this new process holds potential for commercial as well as scientific applications. Upon viewing their new thin films through the powerful transmission electron microscopes at NCEM, the Berkeley Lab scientists found they could easily vary the composition and structure in order to make a variety of different products, including multilayer films with alternating magnetic layers.
