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787 results on '"Singh, Fouran"'

1. Synergetic effect of edge states and point defects to tune ferromagnetism in CVD-grown vertical nanostructured MoS2: A correlation between electronic structure and theoretical study

Author

Dey, Sharmistha, Srivastava, Pankaj, Phutela, Ankita, Bhattacharya, Saswata, Singh, Fouran, and Ghosh, Santanu

Subjects
Condensed Matter - Materials Science
Abstract

Room-temperature ferromagnetism (RTFM) exhibited by nanostructured two-dimensional semiconductors for spintronics applications is a fascinating area of research. The present work reports on the correlation between the electronic structure and magnetic properties of defect-engineered nano-structured MoS2 thin films. Low-energy light and heavy-mass ion irradiation have been performed to create defects and tune magnetic properties. Vertical nanosheets with edge state termination in the pristine sample have been examined by field emission scanning electron microscopy (FESEM). Deterioration of vertical nanosheets is observed in low-energy Ar+ and Xe+ irradiated samples. An appreciably high magnetization value of 1.7 emu/g was observed for edge-oriented nanostructured pristine MoS2 thin films, which decreased after ion irradiation. From X-ray photoelectron spectroscopy (XPS) data, it is evident that, due to oxygen incorporation in the sulfur vacancy sites, Mo5+ and 6+ states increase after ion irradiation. The density functional theory (DFT) calculations suggest that the edge-oriented spins of the prismatic edges of the vertical nanosheets are primarily responsible for the high magnetic moment in the pristine film, and the edge degradation and reduction in sulfur vacancies by the incorporation of oxygen upon irradiation result in a decrease in the magnetic moment.

Published
2024

4. Influence of swift heavy ion irradiation on structure and morphology of La0.25Pr0.375Ca0.375MnO3 perovskite film

Author

Bhatt, Harsh, Kumar, Yogesh, Tokas, R. B., Singh, A. P., Singh, Fouran, and Singh, Surendra

Subjects
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract

The effects of Ag15+ (120 MeV) swift heavy ion irradiation on the structural and morphological properties of epitaxial La0.25Pr0.375Ca0.375MnO3 (LPCMO) thin films was investigated by x-ray scattering and atomic force microscopy (AFM) techniques. LPCMO films of thickness ~ 280 {\AA} were irradiated with an Ag15+ ion beam at different fluences of 1E11, 5E11, and 1E12 ions/cm2. XRD results suggested the development of the tensile stress along the out-of-plane direction of the LPCMO film upon ion irradiation which increased on increasing the ion fluence. The morphology of the film also modified with the irradiation and an increase in the fluence of the ion beam enhanced the in-plane height-height correlation length scale (grain size) with a loss of the fractal behaviour.

Published
2023

43. Role of Carrier Concentration in Swift Heavy Ion Irradiation Induced Surface Modifications

Author

Gupta, Sushant, Singh, Fouran, Sulania, Indra, and Das, B.

Subjects
Condensed Matter - Materials Science
Abstract

Highly conducting $SnO_{2}$ thin films were prepared by chemical spray pyrolysis technique. One set of as-deposited films were annealed in air for 2 h at 850$^{o}$C. These as-deposited and annealed films were irradiated using $Au^{9+}$ ions with energy of 120 MeV at different fluences ranging from $1\times10^{11}$ to $3\times10^{13}$ $ions/cm^{2}$. Electrical measurement shows that as-deposited $SnO_{2}$ films are in conducting state with n = $3.164 \times 10^{20}$ $cm^{-3}$ and annealed $SnO_{2}$ films are in insulating state. The amorphized latent tracks are created only above a certain threshold value of $S_{e}$, which directly depends on the free electron concentration (n). The electronic energy loss ($S_{e}$) of 120 MeV $Au^{9+}$ ions in $SnO_{2}$ is greater than the threshold energy loss ($S_{eth}$) required for the latent track formation in annealed $SnO_{2}$ thin film, but is less than $S_{eth}$ required for as-deposited $SnO_{2}$ film. Therefore, the latent tracks are formed in the annealed $SnO_{2}$ film and not in the as-deposited $SnO_{2}$ film. Thermal spike model is used for the calculation of threshold energy loss and radius of melted zone. The possible mechanism of the structural changes and surface microstructure evolutions is briefly discussed in the light of ion's energy relaxation processes and target's conductivity. The atomic force microscopy (AFM) study of films shows that the morphologies of irradiated films are linked with carrier concentration of target materials., Comment: 13 pages, 5 figures, 3 tables, 79 references. arXiv admin note: substantial text overlap with arXiv:1512.06119

Published
2016
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50. Swift Heavy Ion Irradiation Induced Modifications in Structural, Microstructural, Electrical and Magnetic Properties of Mn Doped $SnO_{2}$ Thin Films

Author

Gupta, Sushant, Singh, Fouran, and Das, B.

Subjects
Condensed Matter - Materials Science
Abstract

In this paper, we have presented the impact of swift heavy ion beam irradiation on the structural, microstructural, electrical and magnetic properties of $Sn_{0.9}Mn_{0.1}O_{2}$ thin films. The structural and electrical results have been interpreted by using properties of native or point defects, whereas the magnetic and morphological variations have been explained in terms of conductivity of material. Efforts have been made to summarize the properties of all possible charged and neutral point defects ($V_{Sn}^{4-}$, $Sn_{i}^{4+}$, $V_{O}^{0}$, $O_{i}^{2-}$, $Sn_{O}^{4+}$, $O_{Sn}^{2-}$, $H_{O}^{+}$) and afterwards from the correlation between experimentally-observed and theoretically-calculated results various interesting conclusions have been drawn., Comment: 26 pages, 18 figures, 6 tables, 156 references

Published
2015

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