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arXiv · 0802.3984

Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La0.5Ba0.5CoO3: Impact upon Magnetotransport Properties

Eeva Leena Rautama·Philippe Boullay·Asish K. Kundu·Vincent Caignaert·Valerie Pralong·Maarit Karppinen·Bernard Raveau
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Abstract

The synthesis and structural study of the stoichiometric perovskite La0.5Ba0.5CoO3 have allowed three forms to be isolated. Besides the disordered La0.5Ba0.5CoO3 and the perfectly ordered layered LaBaCo2O6, a third form called nanoscale-ordered LaBaCo2O6, is obtained. As evidenced by transmission electron microscopy investigations, the latter consists of 112-type 90 degree oriented domains fitted into each other at a nanometer scale which induce large strains and consequently local atomic scale lattice distortions. These three ferromagnetic perovskites exhibit practically the same Tc (174-179 K), but differently from the other phases, the nanoscale-ordered LaBaCo2O6 is a hard ferromagnet, with Hc = 4.2 kOe, due to the strains which may pin domain walls, preventing the reversal of the spins in a magnetic field. The magnetotransport properties of these phases show that all of them exhibit a maximum intrinsic magnetoresistance, close to 6-7 % around Tc under 70 kOe but that the ordered phase exhibits a much higher tunnelling magnetoresistance effect at low temperature of about 15 % against 4 % due to the grain boundary effects.

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Eeva Leena Rautama, Philippe Boullay, Asish K. Kundu, Vincent Caignaert, Valerie Pralong, Maarit Karppinen, Bernard Raveau. 2008-02-27. Cationic Ordering and Microstructural Effects in the Ferromagnetic Perovskite La0.5Ba0.5CoO3: Impact upon Magnetotransport Properties. https://arxiv.org/abs/0802.3984

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