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Your search keyword '"Sahu, D. R."' showing total 3 results
Start Over Author "Sahu, D. R." Search Limiters Peer Reviewed Topic magnetic properties
3 results on '"Sahu, D. R."'

1. Magnetic properties of La0.6Sr0.4MnO3 thin films on SrTiO3 and buffered Si substrates with varying thickness.

Author

Pradhan, A. K., Hunter, D., Williams, T., Lasley-Hunter, B., Bah, R., Mustafa, H., Rakhimov, R., Zhang, J., Sellmyer, D. J., Carpenter, E. E., Sahu, D. R., and Huang, J.-L.

Subjects
MAGNETICS, THIN films, MAGNETIC properties, HIGH temperatures, PHYSICS
Abstract

La0.60Sr0.40MnO3 (LSMO) thin films of varying thickness from 12 to 55 nm were deposited using the pulsed-laser deposition technique onto single-crystalline SrTiO3 (STO) and STO-buffered Si substrates. The Tc of LSMO films grown on STO-buffered Si substrates decreases faster than films directly grown on STO with decreasing film thickness. The LSMO/STO film with thickness of 55 nm shows Tc at about 360 K, which is close to the bulk value, whereas Tc LSMO film on STO-buffered Si film of similar thickness is reduced to 320 K. This difference is attributed to the strain and interfacial disorders in LSMO film on STO/Si. The film surface morphology is influenced by the film thickness. Oxygenation of LSMO films on STO-buffered Si affects the Tc minimally but improved the overall magnetization of the films due to better oxygenation, which is also the case for postannealing the sample at elevated temperatures. The thermomagnetic history effects observed in LSMO films of STO-buffered Si indicate the presence of inhomogeneity, mostly at the interface, which influences the magnetic properties significantly. [ABSTRACT FROM AUTHOR]

Published
2008
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2. Investigation of CMR Properties in Perovskite Manganites.

Author

Sahu, D. R. and Roul, B. K.

Subjects
*MANGANITE, *PEROVSKITE, *MAGNETORESISTANCE, *OXIDES, *TEMPERATURE effect
Abstract

The interesting interactions among charge, spin and lattice degrees of freedom make the perovskite-based colossal magnetoresistance (CMR) materials very attractive for theoretical and experimental investigation. Since the discovery of CMR materials, there has been extensive study on these materials because of their novel physical properties and potential applications. The physical properties of these samples are usually dependent on their preparation routes. In the present work, nanosized La0.7Sr0.3MnO3 (LSMO) and La0.67Ca0.33 MnO3 (LCMO) perovskite oxides were prepared at relatively low calcined temperature and the structural, magnetic and transport properties were studied and reviewed. The size and topography of the oxides are dependent on the calcinating temperature of the precursors. The magnetization of LSMO and LCMO nanophase is strikingly dependent on the particle size. The transport and magnetoresistive properties of the samples are strongly depend on the sintering temperature. A substantial decrease in the insulator-metal transition temperature and an enhancement in resistivity are found on lowering the sintering temperature. LSMO and LCMO shows enhanced ferromagnetic transition temperature as high as 372 and 265 K respectively. Furthermore, it is also well known that the materials should be in the form of thin film in view with the practical application. So the thin films of LSMO and LCMO were fabricated on Si substrate using this nano-sized powder compacted target. It is observed that film exhibiting CMR can be grown on Si(100) without any buffer layer using this nanosized powder compacted target material. The effects of annealing on the properties of LSMO and LCMO thin film are also reviewed here. As-grown films show a lower metal-insulator transition (TMI) temperature than annealed films. As the annealing temperature increases, significantly higher TMI values are observed. We suggest that the increase of effective hole doping, induced by cationic vacancies due to the excess oxygen, is a possible reason for the observed trend in TMI. Annealing improves the magnetic homogeneity of the grain and grain boundaries. These improvements are favorable to enhance the intrinsic properties of the compound especially the decrease of resistivity. The decrease in resistivity induces the MR ratio to increase. [ABSTRACT FROM AUTHOR]

Published
2008
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3. Enhanced room-temperature magnetoresistance in partially melted La[sub 0.67]Ca[sub 0.33]MnO[sub 3] manganites.

Author

Pradhan, A. K., Pradhan, A.K., Roul, B. K., Roul, B.K., Wen, J. G., Wen, J.G., Ren, Z. F., Ren, Z.F., Muralidhar, M., Muradlihar, M., Dutta, P., Sahu, D. R., Sahu, D.R., Mohanty, S., Patro, P. K., and Patro, P.K.

Subjects
POLYCRYSTALS, MAGNETORESISTANCE, SINTERING, TRANSITION temperature, MAGNETIC properties
Abstract

We have performed magnetic and transport measurements on La[sub 0.67]Ca[sub 0.33]MnO[sub 3] polycrystalline and partially melted samples. The magnetization and resistance decrease as sintering temperature is increased. The insulator-to-metal transition temperature is remarkably enhanced in the partially melted sample, enabling its possible applications at room temperature. The microscopic studies in melt samples show an excellent connectivity between grains, suggesting the enhancement of percolative transport by opening new conduction channels and the disappearance of magnetic phase boundary at elevated temperature by the ordering of Mn spins blocked at the grain boundary of sintered samples. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000
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