A5040612921- 2D Materials and Applications
- Graphene research and applications
- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Topological Materials and Phenomena
- Chalcogenide Semiconductor Thin Films
- MXene and MAX Phase Materials
- Advanced Condensed Matter Physics
- Advanced Thermoelectric Materials and Devices
- Magnetic and transport properties of perovskites and related materials
- Perovskite Materials and Applications
- Electronic and Structural Properties of Oxides
- Heusler alloys: electronic and magnetic properties
- Advanced Memory and Neural Computing
- Multiferroics and related materials
- Molecular Junctions and Nanostructures
- High-pressure geophysics and materials
- Solid-state spectroscopy and crystallography
- Machine Learning in Materials Science
- Organic and Molecular Conductors Research
- Quantum Dots Synthesis And Properties
- Iron-based superconductors research
- Hydrogen Storage and Materials
- Thermal properties of materials
University of Cambridge
2022-2025
University of Delaware
2017-2022
Indian Institute of Science Bangalore
2015-2017
Trinity College Dublin
2012-2017
Advanced Materials and BioEngineering Research
2016-2017
National University of Singapore
2015
Density functional theory is used to systematically study the electronic properties of doped MoS${}_{2}$ monolayers, where dopants are incorporated both via S/Mo substitution or as adsorbates. Among possible substitutional at Mo site, Nb identified suitable $p$-type dopant, while Re donor with lowest activation energy. When simply adsorbed on a monolayer we find that alkali metals shift Fermi energy into conduction band, making system $n$ type. Finally, adsorption charged molecules...
Ab-initio density functional theory calculations are performed to study the electronic properties of a MoS2 monolayer deposited over SiO2 substrate in presence interface impurities and defects. When is placed on defect-free oxide plays an insignificant role, since conduction band top valence minimum located approximately middle band-gap. However, if Na O dangling bonds introduced at surface, these lead localized states, which modulate conductivity from n- p-type. Our results show that...
Ultrathin ferroelectric semiconductors with high charge carrier mobility are much coveted systems for the advancement of various electronic and optoelectronic devices. However, in traditional oxide insulators, transition temperature decreases drastically decreasing material thickness ceases to exist below certain critical owing depolarizing fields. Herein, we show emergence an ordered ground state ultrathin (∼2 nm) single crystalline nanosheets Bi2O2Se at room temperature. Free-standing...
A key challenge in materials discovery is to find high-temperature superconductors. Hydrogen and hydride have long been considered promising displaying conventional phonon-mediated superconductivity. However, the high pressures required stabilize these restricted their application. Here, we present results from high-throughput computation, considering a wide range of high-symmetry ternary hydrides across periodic table at ambient pressure. This large composition space then reduced by...
Abstract Achieving glass‐like ultra‐low thermal conductivity in crystalline solids with high electrical conductivity, a crucial requirement for high‐performance thermoelectrics , continues to be formidable challenge. A careful balance between and transport is essential optimizing the thermoelectric performance. Despite this inherent trade‐off, experimental realization of an ideal material phonon‐glass electron‐crystal (PGEC) nature has rarely been achieved. Here, PGEC‐like AgSbTe 2...
{\it Ab initio} density functional theory calculations are performed to investigate the electronic structure of MoS$_2$ armchair nanoribbons in presence an external static electric field. Such nanoribbons, which nonmagnetic and semiconducting, exhibit a set weakly interacting edge states whose energy position determines band-gap system. We show that, by applying transverse field, $E_\mathrm{ext}$, can be significantly reduced, leading metal-insulator transition beyond certain critical value....
Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have been recently proposed as appealing candidate materials for spintronic applications owing to their distinctive atomic crystal structure and exotic physical properties arising from the large bonding anisotropy. Here we introduce first MoS2-based spin-valves that employ monolayer MoS2 nonmagnetic spacer. In contrast with what is expected semiconducting band-structure of MoS2, vertically sandwiched-MoS2 layers exhibit...
The recently discovered two-dimensional (2D) magnetic insulator CrI$_3$ is an intriguing case for basic research and spintronic applications since it a ferromagnet in the bulk, but antiferromagnet bilayer form, with its ordering amenable to external manipulations. Using first-principles quantum transport approach, we predict that injecting unpolarized charge current parallel interface of bilayer-CrI$_3$/monolayer-TaSe$_2$ van der Waals heterostructure will induce spin-orbit torque (SOT)...
2D materials are well-known to exhibit interesting phenomena due quantum confinement. Here, we show that confinement, together with structural anisotropy, result in an electric-field-tunable Dirac cone black phosphorus. Using density functional theory calculations, find electric field, E_ext, applied normal a phosphorus thin film, can reduce the direct band gap of few-layer phosphorus, resulting insulator-to-metal transition at critical E_c. Increasing E_ext beyond E_c induce system,...
Extreme electronic band convergence and nano/meso-structured phonon scattering leading to ultra-high thermoelectric performance in the near cubic Sb doped GeTe.
Silver vacancy-induced nanoscale cation ordering in AgSbTe 2 elevates its thermoelectric performance.
We demonstrate giant magnetoresistance in $\mathrm{Fe}/\mathrm{MoS}{}_{2}/\mathrm{Fe}$ junctions by means of ab initio transport calculations. show that incorporating either a monolayer or bilayer $\mathrm{MoS}{}_{2}$ are metallic and Fe acts as an efficient spin injector into with efficiency about 45%. This is the result strong coupling between S atoms at interface. For greater thickness, maximum $\ensuremath{\sim}$300% obtained, which remains robust applied bias long tunneling limit. A...
The control of recently observed spintronic effects in topological-insulator/ferromagnetic-metal (TI/FM) heterostructures is thwarted by the lack understanding band structure and spin texture around their interfaces. Here we combine density functional theory with Green's function techniques to obtain spectral at any plane passing through atoms Bi$_2$Se$_3$ Co or Cu layers comprising interface. In contrast widely assumed but thinly tested Dirac cone gapped proximity exchange field, find that...
Spin-memory loss (SML) of electrons traversing ferromagnetic-metal/heavy-metal (FM/HM), FM/normal-metal (FM/NM), and HM/NM interfaces is a fundamental phenomenon that must be invoked to explain consistently large numbers spintronic experiments. However, its strength extracted by fitting experimental data phenomenological semiclassical theory, which replaces each interface fictitious bulk diffusive layer, poorly understood from microscopic quantum framework and/or materials properties. Here...
Two-dimensional (2D) magnetic van der Waals materials provide a powerful platform for studying fundamental physics of low-dimensional magnetism, engineering novel phases, and enabling ultrathin highly tunable spintronic devices. To realize high quality practical devices such applications, there is critical need robust 2D magnets with ordering temperatures above room temperature that can be created via exfoliation. Here the study exfoliated flakes cobalt substituted Fe5GeTe2 (CFGT) exhibiting...
The two-dimensional (2D) semiconductor molybdenum disulfide (MoS2) has attracted widespread attention for its extraordinary electrical, optical, spin and valley related properties. Here, we report on polarized tunneling through chemical vapor deposited (CVD) multilayer MoS2 (~7 nm) at room temperature in a vertically fabricated spin-valve device. A tunnel magnetoresistance (TMR) of 0.5 - 2 % been observed, corresponding to polarization 5 10 the measured range 300 75 K. First principles...
Transition metal dichalcogenides have a laminar structure, with strongly covalently bonded layers weakly interacting through van der Waals forces. They are of special interest also because their unique properties once exfoliated in nanoflakes. We analyze the microstructure oxidized TiS2 nanoflakes atomically resolved scanning transmission electron microscopy and propose comprehensive model for reactivity by means first-principles simulations. In particular we find that reaction to water...
We use a first-principles based self-consistent momentum-resolved density fluctuation (MRDF) model to compute the combined effects of electron-electron and electron-phonon interactions describe superconducting dome in correlated MoS2 thin flake TiSe2. find that without including interaction, coupling transition temperature (Tc) are overestimated both these materials. However, once full angular dynamical fluctuations spin charge induced quasiparticle self-energy included, Tc reduced...
Density functional theory and density perturbation are used to investigate the electronic vibrational properties of TiS2. Within local approximation material is a semimetal both in bulk monolayer form. Most interestingly we observe Kohn anomaly phonon dispersion, which turns into charge wave instability when TiS2 thinned less than four monolayers. Such instability, however, disappears one calculates structure with functional, such as LDA+U, returns an insulating ground state. In this...
Graphene sandwiched between semiconducting monolayers of ferromagnet Cr$_2$Ge$_2$Te$_6$ and transition-metal dichalcogenide WS$_2$ acquires both spin-orbit (SO), valley-Zeeman Rashba types, exchange couplings. Using first-principles combined with quantum transport calculations, we predict that such doubly proximitized graphene within van der Waals heterostructure will exhibit SO torque driven by unpolarized charge current. This system lacking spin Hall current, putatively considered to be...
Liquid-phase exfoliation of layered materials offers a large-scale approach toward the synthesis 2D nanostructures. Structural properties can however change during transition from bulk to state. Any such changes must be examined and understood for successful implementation In this work, we demonstrate nonbulk stacking sequences in few-layer MoS2 WS2 nanoflakes produced by liquid-phase exfoliation. Our analysis shows that derived its counterparts translational shifts layers. No structural...
We investigate the pressure-driven structural and electronic evolution of PdSe\(_2\) using powder X-ray diffraction, Raman spectroscopy, first-principles calculations. Beyond 2.3 GPa, suppression Jahn-Teller distortion induces in-plane lattice expansion metallization. Around 4.8 interlayer \(d_{z^2}-\pi^*\) orbital hybridization drives dimensional crossover, facilitating transformation from 2D distorted to a 3D undistorted pyrite phase. Above 9 novel phase emerges, characterized by...
Abstract Due to their unique energy level structure and high kinetic energy, photoexcited hot carriers exhibit excellent performance from thermally excited in semiconductors. Here, the electrical transport properties of intrinsic monocrystalline silicon at 10 Kelvin, where traditional can be neglected are reported. Compared carriers, several notable differences: an increase carrier mobility ≈2–3 orders magnitude, up ≈10 6 cm 2 Vs −1 ; magnetoresistance ≈5 ≈6.4 × 4 % 1 Tesla, which is more...
We employed {\it in-situ} pulsed laser deposition (PLD) and angle-resolved photoemission spectroscopy (ARPES) to investigate the mechanism of metal-insulator transition (MIT) in NdNiO$_3$ (NNO) thin films, grown on NdGaO$_3$(110) LaAlO$_3$(100) substrates. In metallic phase, we observe three dimensional hole electron Fermi surface (FS) pockets formed from strongly renormalized bands with well-defined quasiparticles. Upon cooling across MIT NNO/NGO sample, quasiparticles lose coherence via a...
Synthesis of room temperature ferroelectric 2D Bi 2 O S ultra-thin nanosheets through a mild chemistry route.