Positive and 'colossal' magnetocaloric effect due to charge ordering in CMR manganites

resumo

The magnetocaloric effect (DeltaS(M)) is studied across the ferromagnetic to charge ordered composition range in Pr1-xCaxMnO3 manganites (0.25 less than or equal to x less than or equal to 0.40). The ferromagnetic phase transition leads to usual entropy decrease on the application of a magnetic field. The charge order transition (T-CO similar to 220-250 K) leads to an uncommon entropy increase, of comparable magnitude (4 J kg(-1) K-1 for 40 kOe). At lower temperatures (T < 50K), close to the field-induced mixed phase, extremely large values of DeltaS(M) are found (for x = 0.32, -20.8 J kg(-1) K-1 for 40 kOe at 26 K). (C) 2003 Elsevier B.V. All rights reserved.

categoria

Materials Science; Physics

autores

Reis, MS; Gomes, AM; Araujo, JP; Tavares, PB; Oliveira, IS; Amaral, VS

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