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Your search keyword '"Sahoo, Krishna Rani"' showing total 29 results
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29 results on '"Sahoo, Krishna Rani"'

1. High-Sensitivity Characterization of Ultra-Thin Atomic Layers using Spin-Hall Effect of Light

Author

Panda, Janmey Jay, Sahoo, Krishna Rani, Praturi, Aparna, Lal, Ashique, Viswanathan, Nirmal K., Narayanan, Tharangattu N., and Rajalakshmi, G.

Subjects
Physics - Optics, Condensed Matter - Materials Science, Physics - Applied Physics
Abstract

Magnetic/non-magnetic/heterostructured ultra-thin films' characterisation is highly demanding due to the emerging diverse applications of such films. Diverse measurements are usually performed on such systems to infer their electrical, optical and magnetic properties. We demonstrate that MOKE-based spin-Hall effect of light (SHEL) is a versatile surface characterization tool for studying materials' magnetic and dielectric ordering. Using this technique, we measure magnetic field dependent complex Kerr angle and the coercivity in ultra-thin films of permalloy (Py) and at molybdenum disulphide (MoS$_2$) - permalloy (MSPy) hetero-structure interfaces. The measurements are compared with standard magneto-optic Kerr effect (MOKE) studies to demonstrate that SHEL-MOKE is a practical alternative to the conventional MOKE method, with competitive sensitivity. A comprehensive theoretical model and simulation data are provided to further strengthen the potential of this simple non-invasive optical method. The theoretical model is applied to extract the optical conductivity and susceptibility of non-magnetic ultra-thin layers such as MoS$_2$ ., Comment: 15 pages, 7 figure, one supplementary document

Published
2022
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2. On the Existence of Photoluminescence and Room-Temperature Spin Polarization in Ambipolar V doped MoS$_2$ Monolayers

Author

Maity, Dipak, Sharma, Rahul, Sahoo, Krishna Rani, Lal, Ashique, Arenal, Raul, and Narayanan, Tharangattu N.

Subjects
Physics - Applied Physics, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

Opto-spintronics is an emerging field where ultra-thin magnetic-semiconductors having high spin-valley coupling play an important role. Here, we demonstrate substitutional vanadium (V) doping in MoS$_2$ lattice in different extent, leading to the coexistence of photoluminescence (PL), valleypolarization (~32%), and valley splitting (~28 meV shift in PL with helicity $\sigma^+$ and $\sigma^-$ of light excitation). A large V doping causes semiconductor to metal transition in MoS$_2$ but with medium level causing the existence of photoluminescence with high spin polarization. The ambipolar nature of medium level V doped MoS$_2$ is shown here indicating its potential as an opto-electronic material. The presence of V-dopants and their different level of content are proven by both spectroscopic and microscopic methods.A detailed temperature and power dependent photoluminescence studies along with density functional theory-based calculations in support unravels the emergence of the co-existence of spin-valley coupling and photoluminescence. This study shows the potential of doping MoS$_2$ for deriving new materials for next generation room temperature opto-spintronics.

Published
2022

3. Neutral atom scattering based mapping of atomically thin layers

Author

Bhardwaj, Geetika, Sahoo, Krishna Rani, Sharma, Rahul, Nath, Parswa, and Shirhatti, Pranav R.

Subjects
Physics - Chemical Physics, Physics - Atomic Physics
Abstract

Imaging surfaces using low energy neutral atom scattering is a relatively recent development in the field of microscopy. In this work we demonstrate that this technique is sensitive enough to distinguish films as thin as a single monolayer from the underlying substrate. Using collimated beams of He and Kr atoms as an incident probe on MoS$_2$ films grown on SiO$_2$/Si substrate, we observe systematic changes in the scattered atom flux which allows us to map the thin MoS$_2$ films. Measurements carried out by varying incidence energy using both He and Kr provides insights into the details of atom-surface collision dynamics and its role in contrast generation., Comment: 17 pages, 14 figures (main text + appendix). Changes from previous version: The discussion section has been updated to account for different possible outcomes of He scattering with surfaces

Published
2021
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6. Tuning the electronic structure of monolayer MoS2 towards metal like via vanadium doping

Author

Maity, Dipak, Sharma, Rahul, Sahoo, Krishna Rani, Lal, Ashique, Arenal, Raul, Narayanan, Tharangattu N., Maity, Dipak, Sharma, Rahul, Sahoo, Krishna Rani, Lal, Ashique, Arenal, Raul, and Narayanan, Tharangattu N.

Abstract

Doping of two-dimensional layered semiconducting materials is becoming pivotal in tailoring their electronic properties, enabling the development of advanced electronic and optoelectronic devices, where the selection of dopant is important. Here, we demonstrate the potential of substitutional vanadium (V) doping in monolayer molybdenum disulfide (MoS2) 2 ) lattice in different extents leading to tunable electronic and optoelectronic properties. We found that low-level V doping ('1 ' 1 at. %) induces p-type characteristics in otherwise n-type monolayer MoS2, 2 , whereas medium-level doping ('5 ' 5 at. %) leads to an ambipolar semiconductor. Degenerately doped MoS2 2 ('9 ' 9 at. %) facilitates a transition from semiconducting towards metallic (metal-like) with reduced electrical resistivity ('4.5 ' 4.5 Q m of MoS2 2 to ' 2 . 2 x 10-5Q - 5 Q m), low activation energy for transport ('11 ' 11 meV), and electric field independent drain current in field effect transistor-based transfer characteristics. A detailed temperature- and power-dependent photoluminescence study along with density functional theory-based calculations in support unravels the emergence of an excitonic transition at ' 850 nm with its intensity dependent on the amount of vanadium. This study shows the potential of V doping in MoS2 2 for generating multifunctional two-dimensional materials for next generation electronics, optoelectronics, and interconnects with systematic control over its electronic structure in a wide range.

Published
2024
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11. Large enhancement of thermal conductivity of aluminum-reduced graphene oxide composites prepared by a single-step method.

Author

Mitra, Arijit, Sahoo, Mihir Ranjan, Samal, Aiswarya, Pradhan, Sunil Kumar, Polai, Balaram, Sahoo, Krishna Rani, Kar, Subrat, Satpathy, Bijoy Kumar, Narayanan, Tharangattu N, Ajayan, Pulickel M, Satyam, Parlapalli V, and Nayak, Saroj K

Subjects
MATERIALS science, METALLIC composites, ALUMINUM, DENSITY functional theory, THERMAL conductivity
Abstract

Metal matrix composites have attracted extensive attention from both the research and industrial perspective. In this study, we prepared aluminum-reduced graphene oxide (Al–rGO) composites with enhanced thermal conductivity in an easy single-step process. Pristine Al shows a thermal conductivity of 175 Wm−1K−1 (standard deviation <5%), which increases to 293 Wm−1K−1 for an Al–rGO composite with 1% rGO. Analysis of theoretical models shows that a higher percentage of rGO inside the Al matrix creates a continuous network resulting in more available phase space through which heat carrier phonons travel with less scattering, and hence thermal conductivity of the composite increases. Furthermore, Al–rGO composites show an ∼5% increase in microhardness compared with pristine Al. The electrical resistivity of the composite is comparable to that of pristine Al for a narrow weight percentage of rGO, whereas a 70% enhancement in the thermal conductivity of the composite is observed for the same weight percentage range, suggesting possibilities for exploiting both high electrical and thermal conductivities for various applications. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Large enhancement of thermal conductivity of aluminum-reduced graphene oxide composites prepared by a single-step method

Author

Mitra, Arijit, primary, Sahoo, Mihir Ranjan, additional, Samal, Aiswarya, additional, Pradhan, Sunil Kumar, additional, Polai, Balaram, additional, Sahoo, Krishna Rani, additional, Kar, Subrat, additional, Satpathy, Bijoy Kumar, additional, Narayanan, Tharangattu N, additional, Ajayan, Pulickel M, additional, Satyam, Parlapalli V, additional, and Nayak, Saroj K, additional

Published
2023
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17. Enhanced room-temperature spin-valley coupling in V-doped MoS2

Author

Department of Atomic Energy (India), Science and Engineering Research Board (India), Department of Science and Technology (India), Universidad de Zaragoza, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Gobierno de Aragón, European Commission, Diputación General de Aragón, Sahoo, Krishna Rani, Panda, Janmey Jay, Bawari, Sumit, Sharma, Rahul, Maity, Dipak, Lal, Ashique, Arenal, Raúl, Rajalaksmi, G., Narayanan, Tharangattu N., Department of Atomic Energy (India), Science and Engineering Research Board (India), Department of Science and Technology (India), Universidad de Zaragoza, Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), Gobierno de Aragón, European Commission, Diputación General de Aragón, Sahoo, Krishna Rani, Panda, Janmey Jay, Bawari, Sumit, Sharma, Rahul, Maity, Dipak, Lal, Ashique, Arenal, Raúl, Rajalaksmi, G., and Narayanan, Tharangattu N.

Abstract

Achieving room-temperature valley polarization in two-dimensional (2D) atomic layers (2D materials) by substitutional doping opens new avenues of applications. Here, monolayer MoS2, when doped with vanadium at low (0.1 atomic %) concentrations, is shown to exhibit high spin-valley coupling, and hence a high degree of valley polarization at room-temperature. The atomic layers of MoS2 (MS) and V-doped MoS2 (VMS) are grown via the chemical vapor deposition-assisted method. The formation of new energy states near the valence band is confirmed from band gap calculations and also from the density functional theory–based band structure analyses. Time-reversal symmetry broken energy shift in the equivalent valleys is predicted in VMS, and the room-temperature chirality-controlled photoluminescent (PL) excitation measurements indicate such a shift in valley exciton energies (∼35 meV). An enhanced valley polarization in VMS (∼42%) is observed in comparison to that in MS (<12%), while in MS, the chirality-controlled excitations did not show the difference in emission energies. Spin Hall effect of light–based optical rotation measurements indicate the asymmetric absorption among the two different chiralities of the incident light, hence supporting the existence of room-temperature valley polarization. This study opens possibilities of room-temperature opto-spintronics using stable 2D materials.

Published
2022

26. Structural and Electronic Transport Properties of Fluorographene Directly Grown on Silicates for Possible Biosensor Applications

Author

Sharma, Rahul, primary, Asmara, Teguh Citra, additional, Sahoo, Krishna Rani, additional, Grage, Stephan L., additional, Zhang, Ruiqi, additional, Sun, Jianwei, additional, Das, Subhabrata, additional, Ulrich, Anne S., additional, Rusydi, Andrivo, additional, Aryasomayajula, Subrahmanyam, additional, Paulmurugan, Ramasamy, additional, Liepmann, Dorian, additional, Kumar, D. Sakthi, additional, Somasundaran, Ponisseril, additional, Renugopalakrishnan, Venkatesan, additional, and Narayanan, Tharangattu N., additional

Published
2020
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29. On the electronic and spin-valley coupling of vanadium doped MoS 2(1- x ) Se 2 x monolayers.

Author

Maity D, Sharma R, Sahoo KR, Panda JJ, Lal A, Puthirath AB, Ajayan PM, and Narayanan TN

Abstract

Monolayers of MoS 2 with tunable bandgap and valley positions are highly demanding for their applications in opto-spintronics. Herein, selenium (Se) and vanadium (V) co-doped MoS 2 monolayers (vanadium doped MoS 2(1- x ) Se 2 x (V-MoSSe)) are developed and showed their variations in the electronic and optical properties with dopant content. Vanadium gets substitutionally (in place of Mo) doped within the MoS 2 lattice while selenium doped in place of sulfur, as shown by a detailed microstructure and spectroscopy analyses. The bandgap tunability with selenium doping can be achieved while valley shift is occurred due to the doping of vanadium. Chemical vapor deposition assisted grown MoS 2 (also selenium doped MoS 2 as shown here) is known for its n-type transport behavior while vanadium doping is found to be changing its nature to p-doping. Chirality dependent photoexcitation studies indicate a room temperature valley splitting in V-MoSSe (∼8 meV), where such a valley splitting is verified using density functional theory based calculations., (© 2023 IOP Publishing Ltd.)

Published
2023
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