ACTA

Magnetic Properties of Oxygen Deficient Y_0.33Sr_0.67CoO_3-δ

Y.F. Zhang^a, S. Sasaki^a, O. Yanagisawa^b and M. Izumi^a
^aLaboratory of Applied Physics, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533, Japan
^bYuge National College of Maritime Technology, Ehime 794-2593, Japan

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Received: 04 09 2006;

We studied magnetic properties of perovskite-type Y_0.33Sr_0.67 CoO_2.614 and Y_0.33Sr_0.67CoO_2.707 prepared under different sintered temperatures at 1250ºC and 1100ºC, respectively. A dc magnetization jump associated with a large thermal hysteresis around 180 K was found in Y_0.33Sr_0.67CoO_2.614, which indicates a kind of magnetic memory effect. On the other hand, Y_0.33Sr_0.67CoO_2.707 shows a larger magnetization with a small magnetization jump around 200 K and lower Curie temperature than those of Y_0.33Sr_0.67CoO_2.614. Rich Co³⁺ ions in the low temperature sintered Y_0.33Sr_0.67CoO_2.707 possibly introduce large magnetization and high magnetization jump temperature. This may be coming from a surface/volume effect of Co³⁺ ions appearing in the polycrystalline sample prepared at low temperature. The ferromagnetism resulted from the different surface/volume ratio contributes to a part of magnetization and may result in the change of the Curie temperature.

DOI: 10.12693/APhysPolA.111.79
PACS numbers: 72.80.Ga, 75.60.-d, 75.70.Rf, 81.40.Rs