GIANT MAGNETORESISTANCE RATIOS SUPERIOR TO 10(11) IN MANGANESE PEROVSKITES

The recent studies of mixed valent manganese perovskites La(1-x)A(x)MnO(3-delta) (A = Ca, Sr, Ba) have shown remarkable giant magneto resistance (GMR) properties. For these oxides fabricated either in the form of thin films [1-8] or of ceramics [9-13], R(o)/R(H) ratios where R(o) and R(H) are the resistances in a zero and applied magnetic field respectively, ranging from 10 to 10(4) have been observed at mu(0)H = 5 or 8T. The recent discovery of the perovskite Pr0.7Sr0.05Ca0.25MnO3-delta [13] with a R(o)/R(H) ratio superior to 2.5.10(5) at 88K with mu(0)H = 5T, slates the issue of the limit of the GMR ratio that can be reached in these compounds, that are of the highest importance for device applications. We report herein on the GMR properties of the parent semi-conductor perovskite Pr0.7Sr0.04Ca0.26MnO3-delta that exhibits a spectacular drop of its resistivity of 11 orders of magnitude by applying a magnetic field of 5T at 30K.