Faculty Publications
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Item Spin transport through metal-dichalcogenides layers: a study from first-principles calculations(IOP Publishing Ltd, 2020) Devaraj, N.; Tarafder, K.Spin transport through monolayer and trilayers of molybdenum dichalcogenides were studied considering Co as leads. Detailed investigations of the electronic structure of the Co/MoS2 interface and magnetic tri-junctions are carried out by using density functional theory calculations to understand transport behavior. The study revealed that new spin-polarized hybridized states appeared at the Fermi level due to the formation of Co/MoS2 interface that effectively acted as a spin filter and enhanced the spin injection efficiency of the systems. Spin-polarized current through the system as well as the magnetoresistance (MR) was estimated at different applied bias voltages. Large MR up to 78% was calculated for the trilayer MoS2 system at a relatively high applied bias voltage. The MR values are further improved by tuning the structure of the scattering region. A very large MR of 123% for MoS2/MoSe2/MoS2 trilayer at an applied bias 0.8 V was observed, which is much higher than the previously reported bias dependent MR values in similar systems. © 2020 IOP Publishing Ltd.Item Large magnetoresistance in a Co/Mo S2/graphene/Mo S2/Co magnetic tunnel junction(American Physical Society, 2021) Devaraj, N.; Tarafder, K.We demonstrate a large magnetoresistance (MR) in a Co/MoS2/graphene/MoS2/Co magnetic tunnel junction by means of ab initio transport calculations. A Co electrode turns out to be an excellent spin injector for a MoS2/graphene/MoS2 barrier. The transmission spectrum, current-voltage characteristics, spin injection efficiency, and magnetoresistance are calculated for the modeled device at various bias voltages in the parallel and antiparallel magnetic configurations. A remarkable change in the transmission spectrum and a subsequent change in total current through the junction have been observed, when the relative magnetic orientations of the electrodes are altered. The huge change in current due to the change in the relative magnetic orientation of the Co electrodes produces a high magnetoresistance up to 1270%. The obtained values of the device parameters clearly indicate that a MoS2/graphene/MoS2 heterostructure would be an excellent compound for highly efficient spin-valve device applications. © 2021 American Physical Society.Item Unprecedented Electroreduction of CO2over Metal Organic Framework-Derived Intermetallic Nano-Alloy Cu0.85Ni0.15/C(American Chemical Society, 2022) Payra, S.; Devaraj, N.; Tarafder, K.; Roy, S.Designing suitable catalysts for efficient and selective electrocatalytic reduction of CO2 is a need of the hour, and in this regard, the well-defined, highly dispersed active metal centers can be a trendsetting research endeavor toward CO2 electroreduction due to the maximum atom utilization and unique electronic structure. This study describes the synthesis and electrocatalytic CO2 reduction activity of atomistically dispersed Cu/C and Ni/C and the intermetallic nano-alloy Cu0.85 Ni0.15 /C. The catalysts were synthesized from the corresponding MOF precursors. The successful synthesis of the monometallic and intermetallic nano-alloys was established from structural, surface morphological, and electronic properties. Cu0.85 Ni0.15 /C exhibited an unprecedented electrocatalytic reduction of CO2 with a high selectivity and high faradaic efficiency toward CH3 OH. The kinetic studies and the first-principles calculations elucidated the intricate mechanism and the superior activity of electrocatalytic reduction of CO2 over the intermetallic Cu0.85 Ni0.15 /C catalyst. © 2022 American Chemical Society. All rights reserved.Item Spin-Transport through Van der Waals Heterojunctions Based on 2D-Ferromagnet and Transition Metal Dichalcogenides: A Study from First-Principles Calculations(John Wiley and Sons Inc, 2022) Devaraj, N.; Tarafder, K.Recently reported 2D ferromagnets show tremendous potential for their application in low-dimensional spintronic devices. Semiconductor heterostructure consisting of 2D ferromagnet integrated with other suitable 2D semiconducting materials may pave the way for designing robust and sophisticated spin-transport devices within a few nanometer scales. In this regard, a detailed understanding of the interface properties of 2D ferromagnetic materials and other 2D semiconductors is highly essential. Herein, the interface properties in the heterostructure made-up of CrX3 (X = Cl, Br, and I) monolayer and transition-metal dichalcogenides (TMDC; MoS2, MoSe2, and WS2) monolayer, using first-principle calculations are systematically studied. This study predicts that a robust spin-dependent barrier originated at the CrX3/TMDC interface. It can lead to a significantly large spin-filtering at the interface while spin-transport through this heterojunction, which will be highly beneficial for spintronic devices applications. Further, detailed spin-dependent transport studies carried out through Co/CrI3/TMDC/CrI3/Co magnetic heterojunctions and substantial tunnel magnetoresistance up to 590%, estimated for these systems. © 2022 Wiley-VCH GmbH.