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Colossal Magnetoresistance in Perovskite-like La-Ca-Mn-O

A colossal magnetoresistance effect with more than four orders of magnitude change in resistivity (ΔR/R H = 10 6 % at 110K, H = 6T) has been obtained in epitaxially grown La-Ca-Mn-O thin films. The effect is negative and isotropic with respect to the field orientations. The magnetoresistance is strongly temperature- dependent, and exhibits a sharp peak that can be shifted to near room temperature by adjusting processing parameters. The very large MR effect occurs only when the film thickness is less than about 2000 A. Near-room-temperature AR/RH values of ∼ 1,300% at 260K and - 400% at 280K have been observed. The orders of magnitude change in electrical resistivity could be useful for various magnetic and electric device applications.