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Full-Text Articles in Nanoscience and Nanotechnology
Role Of Strain On Electronic And Mechanical Response Of Semiconducting Transition-Metal Dichalcogenide Monolayers: An Ab-Initio Study, David M. Guzman, Alejandro Strachan
Role Of Strain On Electronic And Mechanical Response Of Semiconducting Transition-Metal Dichalcogenide Monolayers: An Ab-Initio Study, David M. Guzman, Alejandro Strachan
Birck and NCN Publications
We characterize the electronic structure and elasticity of monolayer transition-metal dichalcogenides MX2 (M = Mo, W, Sn, Hf and X = S, Se, Te) based on 2H and 1T structures using fully relativistic first principles calculations based on density functional theory. We focus on the role of strain on the band structure and band alignment across the series of materials. We find that strain has a significant effect on the band gap; a biaxial strain of 1% decreases the band gap in the 2H structures, by as a much as 0.2 eV in MoS2 and WS2, while increasing it for …
Time-Dependent Density Functional Theory Of Coupled Electronic Lattice Motion In Quasi-Two-Dimensional Crystals, Vladimir U. Nazarov, Fhhad Alharbi, Timothy Fisher, Sabre Kais
Time-Dependent Density Functional Theory Of Coupled Electronic Lattice Motion In Quasi-Two-Dimensional Crystals, Vladimir U. Nazarov, Fhhad Alharbi, Timothy Fisher, Sabre Kais
Birck and NCN Publications
Electron-holes, phonons, and plasmons come in close proximity to each other in the low-energy range of the excitation spectrum of two-dimensional (2D) crystals, breaking the validity of the weakly interacting-quasiparticles picture. By including the lattice oscillations into the scheme of time-dependent density-functional theory, we open a pathway to the ab initio treatment of the coupled low-energy excitations in 2D crystals. With the use of graphene as an important test system, we find the strong coupling of the elementary excitations, giving rise to new hybrid collective modes. The total (including both the electronic and ionic response) dielectric function epsilon(tot)(omega) is constructed …
Quantum And Classical Magnetoresistance In Ambipolar Topological Insulator Transistors With Gate-Tunable Bulk And Surface Conduction, Jifa Tian, Cuizu Chang, Helin Cao, Ke He, Xucun Ma, Qikun Xue, Yong P. Chen
Quantum And Classical Magnetoresistance In Ambipolar Topological Insulator Transistors With Gate-Tunable Bulk And Surface Conduction, Jifa Tian, Cuizu Chang, Helin Cao, Ke He, Xucun Ma, Qikun Xue, Yong P. Chen
Birck and NCN Publications
Weak antilocalization (WAL) and linear magnetoresistance (LMR) are two most commonly observed magnetoresistance (MR) phenomena in topological insulators (TIs) and often attributed to the Dirac topological surface states (TSS). However, ambiguities exist because these phenomena could also come from bulk states (often carrying significant conduction in many TIs) and are observable even in non-TI materials. Here, we demonstrate back-gated ambipolar TI field-effect transistors in (Bi0.04Sb0.96)(2)Te-3 thin films grown by molecular beam epitaxy on SrTiO3(111), exhibiting a large carrier density tunability (by nearly 2 orders of magnitude) and a metal-insulator transition in the bulk (allowing switching off the bulk conduction). Tuning …
Prediction Of Spectral Phonon Mean Free Path And Thermal Conductivity With Applications To Thermoelectrics And Thermal Management: A Review, Tianli Feng, Xiulin Ruan
Prediction Of Spectral Phonon Mean Free Path And Thermal Conductivity With Applications To Thermoelectrics And Thermal Management: A Review, Tianli Feng, Xiulin Ruan
Birck and NCN Publications
We give a review of the theoretical approaches for predicting spectral phonon mean free path and thermal conductivity of solids. The methods can be summarized into two categories: anharmonic lattice dynamics calculation and molecular dynamics simulation. In the anharmonic lattice dynamics calculation, the anharmonic force constants are used first to calculate the phonon scattering rates, and then the Boltzmann transport equations are solved using either standard single mode relaxation time approximation or the Iterative Scheme method for the thermal conductivity. The MD method involves the time domain or frequency domain normal mode analysis. We present the theoretical frameworks of the …