Sep 12 – 17, 2010
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Magnetic and electrical transport properties of Ce/Ca substituted perovskite oxides

Not scheduled
500/1-001 - Main Auditorium (CERN)

500/1-001 - Main Auditorium


CH - 1211 Geneva 23 Switzerland
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POSTER Magnetism and Magnetic materials - Bulk and thin layers


M. P. Sharma (University of Rajasthan, Jaipur (India))


Magnetic and electric transport studies have been made on cerium-calcium substituted perovskites La1-2xCexCaxMnO3 for x = 0.05, 0.10 and 0.15, prepared by solgel method. Magnetization and electrical measurements are reported in the temperature range 20K – 300K and in fields upto 8 kOe and 2K – 300K and in fields upto 14 T respectively. All the samples undergo paramagnetic to ferromagnetic transition. Among the Ce/Ca substituted samples LCeCaM15 is highly disordered. Addition of 10 atomic% Ca into 10 atomic% Ce substituted system drives the FM state towards a more disordered one and when in place of 10 atomic% Ce, the substitution is of 5 atomic% Ce and 5 atomic% Ca, the system shows up to be far better FM ordered. In the series La1-2xCexCaxMnO3 no upturn is seen in resistivity but there is only a slight tendency of increase at ~30K [Figure 1]. This would mean that in the Ce/Ca substituted samples, of the two competing factors – decreasing scattering with lowering of temperature leading to reduction in resistivity and spin polarized tunneling leading to enhancement of resistivity - the factor of decreasing scattering overtakes. In insulating regions of all the samples, at temperatures above the M – I transition points, conduction is controlled by variable range hopping and at higher temperatures small polaron hopping mechanism is operative [1]. Values of activation energy are much smaller those reported in other substituted manganites [2]. The magnetoresistance (MR), plot shown in Fig. 1 as a function of temperature, is observed to be negative and large. For all the three samples, under 5 T field it is as high as ~40% at temperatures close to I – M transition and under 14 T the maximum is ~68% for LCeCaM05. At 300K and under 5 T field it is close to 15% for all the samples.
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Primary author

M. P. Sharma (University of Rajasthan, Jaipur (India))


Prof. Anjali Krishnamurthy (Department of Physics, University of Rajasthan, Jaipur) Prof. Bipin K. Srivastava (Department of Physics, University of Rajasthan, Jaipur) Dr V. Ganesan (UGC-DAE Consortium for Scientific Research, Indore)

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