Magnetic phase evolution in Fe substituted GdBaCo2O5.5 |
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Authors: | N. Thirumurugan C.S. Sundar |
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Affiliation: | Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, India |
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Abstract: | Magnetization and magneto-resistance experiments have been carried out on well characterized samples of the GdBaCo2−xFexO5.5 series. Zero field cooled magnetization measurements in the low concentration Fe samples suggest, that the low temperature anti-ferromagnetic phase transforms sequentially to several ferromagnetic phases, before transforming to a paramagnetic state with increase in temperature. The anti-ferromagnetic to the first ferromagnetic phase transition is associated with a large negative magneto-resistance for Fe fractions upto x=0.075. Isothermal magnetization measurements in the ferromagnetic like region of the samples, suggests the presence of mixtures of two ferromagnetic phases. Similar measurements performed at low temperatures where anti-ferromagnetic-like phase is stabilised suggest the presence of a mixture of anti-ferromagnetic and ferromagnetic phases. Magnetization and magneto-resistance are seen to collapse for Fe fractions, x>0.1. Based on these studies a plausible scenario of the evolution of magnetism with Fe substitution in GdBaCo2O5.5, is suggested. |
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Keywords: | Cobaltates Phase separation Magnetization Magnetoresistance |
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