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|Type:||Artigo de periódico|
|Title:||Effects Of Ru Doping On The Transport And Magnetic Properties Of A La 1.32sr1.68mn2 - Yruyo7 Layered Manganite System|
|Abstract:||The low temperature magnetization, specific heat, electrical resistance and magnetoresistance have been studied for the Ru-doped La1.32Sr 1.68Mn2 - yRuyO7 (y = 0.0, 0.04, 0.08 and 0.15) layered manganite system. The undoped compound (y = 0.0) shows a sharp ferromagnetic transition (TC) accompanied by a metal-insulator transition (TMI) at 118K. The Ru substitution decreases the T C and TMI temperatures significantly. The temperature dependence of specific heat measurement confirms the decrease in TC by observing the anomaly corresponding to TC. The decreased effective moments from 3.48 μB for the undoped compound to 1.82μB for the highly doped compound at 5K indicates the Ru substitution weakens the ferromagnetic order in the low temperature regime and reduces the number of Mn pairs in the highly doped sample. The field dependence of magnetization measurements exhibits an enhancement of the coercive field with increased Ru concentration and gives evidence for the mixed magnetic phase for the highly doped compound. For the undoped sample, a large negative magnetoresistance of 300% at TC and 128% at 4.2K in a 5T field were observed. The magnetoresistance ratio decreases gradually with increasing Ru substitution. We find that the doped Ru in the Mn site drives the layered manganite system towards a magnetically mixed state. The effects of Ru doping in the transport and magnetic properties will be explained by the antiferromagnetically coupled Ru and Mn sublattices. © 2010 IOP Publishing Ltd.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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