| 1. |
- Jayakumar, O. D., et al.
(author)
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1D Morphology Stabilization and Enhanced Magnetic Properties of Co : ZnO Nanostructures on Codoping with Li: A Template-Free Synthesis
- 2009
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In: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 9:10, s. 4450-4455
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Journal article (peer-reviewed)abstract
- ID natiostructures of Zn1-xCoxO (x = 0, 0.03 and 0.05) and Co and Li codoped ZnO (Zn0.85Li0.10Co0.05O) were prepared by a soft chemical method. We report a very interesting observation of morphological control and transformation of ZnO nanorods to spherical particles induced by Co substitution. It is also remarkable to note that the morphology completely reverts back to rod shape by Li incorporation. In addition to this unusual observation, the Li incorporation enhances the room-temperature ferromagnetic (RTFM) properties. These experimental observations are well-supported by theory work as well. These results are significant, as the I D RTFM will have implications in spintronic devices.
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| 2. |
- Jayakumar, O. D., et al.
(author)
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Surfactant-induced enhanced room temperature ferromagnetism in Zn0.96Mn0.03Li0.01O nanoparticles : Prepared by solid-state pyrolitic reaction
- 2007
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In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 307:2, s. 315-320
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Journal article (peer-reviewed)abstract
- We report the synthesis of nanoparticles of Zn0.96Mn0.03Li0.01O by a low-temperature solid-state pyrolitic reaction, followed by a surfactant-assisted calcination at 400 degrees C. The X-ray diffraction and transmission electron microscopy analyses showed the formation of impurity free nanocrystals of Mn doped Li co-cloped ZnO with wurtzite structure. XPS data revealed that Mn exists in + 2 oxidation state. DC magnetization measurements as a function of field and temperature showed enhanced room temperature ferromagnetism for the surfactant-treated Zn0:96Mn0.03Li0.01O. FMR signal observed in the EPR spectrum further confirmed its ferromagnetic nature.
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| 3. |
- Nagar, Sandeep, et al.
(author)
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Room Temperature Ferromagnetism and Lack of Ferroelectricity in Thin Films of 'Biferroic?' YbCrO3
- 2009
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In: Novel Materials and Devices for Spintronics. - : Materials Research Society. - 9781605111568 ; , s. 163-168
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Conference paper (peer-reviewed)abstract
- Search for novel multi-functional materials, especially multiferroics, which are ferromagnetic above room temperature and at the same time exhibit a ferroelectric behavior much above room temperature, is an active topic of extensive studies today Ability to address an entity with an external field, laser beam, and also electric potential is a welcome challenge to develop multifunctional devices enabled by nanoscience While most of the studies to date have been on various forms of Bi and Ba based Ferrites, rare earth chromites are a new class of materials which appear to show some promise However m the powder and bulk form these materials are at best canted antiferromagnets with the magnetic transition temperatures much below room temperature In this presentation we show that thin films of YbCrO3 deposited by Pulsed Laser Deposition exhibit robust ferromagnetic properties above room temperature It is indeed a welcome surprise and a challenge to understand the evolution of above room temperature ferromagnetism in such a thin film The thin films are amorphous in contrast to the powder and bulk forms which are crystalline The magnetic properties are those of a soft magnet with low coercivity We present extensive investigations of the magnetic and ferroelectric properties, and spectroscopic studies using XAS techniques to understand the electronic states of the constituent atoms in this novel Chromite While the amorphous films are ferromagnetic much above room temperature, we show that any observation of ferroelectric property in these films is an artifact of a leaky highly resistive material
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