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Metal-insulator transition induced by 16O -18O oxygen isotope exchange in colossal negative magnetoresistance manganites

N. A. Babushkina·L. M. Belova·V. I. Ozhogin·O. Yu. Gorbenko·A. R. Kaul·A. A. Bosak·D. I. Khomskii·K. I. Kugel
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Abstract

The effect of 16O-18O isotope exchange on the electric resistivity was studied for (La(1-y)Pr(y))0.7Ca0.3MnO3 ceramic samples. Depending on y, this mixed perovskite exhibited different types of low-temperature behavior ranging from ferromagnetic metal (FM) to charge ordered (CO) antiferromagnetic insulator. It was found that at y=0.75, the substitution of 16O by 18O results in the reversible transition from a FM to a CO insulator at zero magnetic field. The applied magnetic field (H >= 2 T) transformed the sample with 18O again to the metallic state and caused the increase in the FM transition temperature Tc of the 16O sample. As a result, the isotope shift of Tc at H = 2 T was as high as 63 K. Such unique sensitivity of the system to oxygen isotope exchange, giving rise even to the metal-insulator transition, is discussed in terms of the isotope dependence of the effective electron bandwidth which shifts the balance between the CO and FM phases.

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N. A. Babushkina, L. M. Belova, V. I. Ozhogin, O. Yu. Gorbenko, A. R. Kaul, A. A. Bosak, D. I. Khomskii, K. I. Kugel. 1998-05-25. Metal-insulator transition induced by 16O -18O oxygen isotope exchange in colossal negative magnetoresistance manganites. https://doi.org/10.1063/1.367636

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