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On the factors affecting the high temperature insulator-metal transition in rare-earth manganites

Dipten Bhattacharya·Pintu Das·A. Pandey·A. K. Raychaudhuri·Amitava Chakraborty·V. N. Ojha
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Abstract

The measurement of resistivity across a wide temperature range - from 15 to 1473 K - in rare-earth manganite series of compounds reveals a very interesting feature : normally observed insulating pattern beyond Tc (Curie Point) gives way to a reentrant metallic pattern around a characteristic temperature T*. The transport activation barrier Ea collapses to zero around T*. T* is found to be dependent on the carrier concentration or the concentration of the Jahn-Teller-active Mn(3+) ions as well as on the average A-site radius for a fixed carrier concentration. These factors govern the effective lattice distortion and hence lead to the variation in the conduction bandwidth. Our data cover a wide range - from T*>>Tc for smaller bandwidth to T* tending towards Tc for larger bandwidth. These results seem to provide evidence of the onset of lattice distortion at high temperature (around T*) and its variation. Since lattice distortion governs the magnetic, transport and other important behaviors significantly, our data assume importance as they offer a new measure of the effective distortion and its tunability.

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Dipten Bhattacharya, Pintu Das, A. Pandey, A. K. Raychaudhuri, Amitava Chakraborty, V. N. Ojha. 2000-11-21. On the factors affecting the high temperature insulator-metal transition in rare-earth manganites. https://doi.org/10.1088/0953-8984%2F13%2F20%2F106

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