A CLASS OF COBALT OXIDE MAGNETORESISTANCE MATERIALS DISCOVERED WITH COMBINATORIAL SYNTHESIS

The recent development of methods for generating libraries of solid-st ate compounds has made it possible to apply combinatorial approaches t o the discovery of materials. A library of 128 members containing diff erent compositions and stoichiometries of Ln(x)M(y)CoO(delta), where L n = Y or La and M = Pb, Ca, Sr, or Ba, was synthesized by a combinatio n of thin-film deposition and physical masking techniques. Large magne toresistance has been found in La-x(Ba,Sr,Ca)(y)-CoOdelta samples, whe reas Y-based samples exhibit much smaller magnetoresistive effects. Th e magnetoresistance of the Co-containing compounds increases as the si ze of the alkaline earth ion increases, in sharp contrast to Mn-contai ning compounds, in which the magnetoresistance effect increases as the size of the alkaline earth ion decreases.