Colossal magnetoresistance in La-Y-Ca-Mn-O films

Magnetoresistance behavior of La/sub 0.60/Y/sub 0.07/CaMnO/sub x/ thin films epitaxially grown on LaAlO/sub 3/ has been investigated. The films exhibit colossal magnetoresistance with the MR ratio in excess of 10/sup 8/% at -60 K, H=7T, which is the highest ever reported for thin film manganites. The partial substitution of La/sup 3+/ ions with much smaller Y/sup 3+/ ions results in mote than an order of magnitude improvement in MR as compared to the undoped La-Ca-Mn-O material, both in bulk and thin film form. The La-Y-Ca-Mn-O films exhibit a strong dependence of magneto-resistance on film thickness with the maximum MR occuring at a film thickness of -1000.