Electrochemical oxidation and reduction of the La0.2Sr0.8CoO3−δ phases: Control of itinerant ferromagnetism and magnetoresistance |
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| Affiliation: | 1. INFIQC (CONICET − Universidad Nacional de Córdoba), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre esq. Medina Allende, Ciudad Universitaria, X5000HUA Córdoba, Argentina;2. INQUINOA (CONICET- UNT). Instituto de Química Física, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, San Lorenzo 456, T4000CAN Tucumán, Argentina;3. Institut Néel, CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9, France;4. Departamento de Física. UEM. Av. Colombo, 5790, Maringá, PR, Brazil;5. Instituto de Química Inorgánica; Facultad de Bioquímica, Química y Farmacia; Universidad Nacional de Tucumán. Ayacucho 471. 4000. San Miguel de Tucumán. Argentina;6. Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, CONICET and Instituto Balseiro, Universidad Nacional de Cuyo, (8400) San Carlos de Bariloche (RN), Argentina |
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| Abstract: | In order to understand how the magnetotransport properties are related to the oxygen content, the La0.2Sr0.8CoO3−δ perovskite phases have been studied by using electrochemical cycling. The samples, prepared by a sol–gel technique, have been characterized from a structural and chemical point of view concomitantly to their physical properties. Upon reduction, a brownmillerite-type phase La0.2Sr0.8CoO2.65, which presents a weak ferromagnet behavior, is formed and, upon oxidation, a complete stoichiometric phase with a cubic unit cell (a = 3.83Å) could be obtained with a ferromagnetic and metallic behavior. Finally, it is shown that using appropriate cut-off potential upon reduction or oxidation the oxygen content and the cobalt valence can be monitored in such transition metal oxides to reach the fully oxidized or reduced end-members. |
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