scholarly journals Spin-Filtering Effects in Würtzite and Graphite-Like AlN Nanowires with Mn Impurities

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
G. A. Nemnes
Keyword(s):  
Phase Transition ◽  
Density Functional ◽  
Surface States ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Group Iii ◽  
Magnetic Nanowire ◽  
Group Iii Nitride ◽  
Basic Prerequisite ◽  
Spin Filtering

Spin transport properties of magnetic nanowire systems—atomic-sized AlN nanowires with additional Mn impurities—are investigated employingab initioconstrained spin density functional theory calculations and nonequilibrium Green’s functions formalism. The analyzed nanowire structures exhibit a stress-induced phase transition, between würtzite and graphite-like configurations. In these quasi-one dimensional systems, the surface states ensure the basic prerequisite in establishing spin and charge transfer, by reducing the relatively large bandgap of the group III nitride semiconductor. The results show in how far this phase transition affects the surface states, focusing on the consequences which appear in the spin-filtering processes.

scholarly journals Predicted polymorph manipulation in an exotic double perovskite oxide

2019 ◽  
Vol 7 (39) ◽  
pp. 12306-12311 ◽  
Author(s):  
He-Ping Su ◽  
Shu-Fang Li ◽  
Yifeng Han ◽  
Mei-Xia Wu ◽  
Churen Gui ◽  
...  
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Double Perovskite ◽  
Density Functional Theory Calculations ◽  
Perovskite Oxide ◽  
Functional Theory ◽  
First Time ◽  
Perovskite Type

First-principles density functional theory calculations, for the first time, was used to predict the Mg3TeO6-to-perovskite type phase transition in Mn3TeO6 at around 5 GPa.

Janus monolayer of WSeTe, a new structural phase transition material driven by electrostatic gating

Nanoscale ◽  
2018 ◽  
Vol 10 (46) ◽  
pp. 21629-21633 ◽  
Author(s):  
Yajing Sun ◽  
Zhigang Shuai ◽  
Dong Wang
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
Structural Phase Transition ◽  
Density Functional ◽  
Structural Phase ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Electrostatic Gating ◽  
Phase Transition Kinetics

By density functional theory calculations, we show that the Janus monolayer of WSeTe has faster semiconductor–semimetal phase transition kinetics than MoTe2.

scholarly journals Crossover from metal to insulator in dense lithium-rich compound CLi4

2016 ◽  
Vol 113 (9) ◽  
pp. 2366-2369 ◽  
Author(s):  
Xilian Jin ◽  
Xiao-Jia Chen ◽  
Tian Cui ◽  
Ho-kwang Mao ◽  
Huadi Zhang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
Fermi Surface ◽  
Density Functional ◽  
Alkali Metals ◽  
Alkaline Earth ◽  
Density Functional Theory Calculations ◽  
Alkaline Earth Metals ◽  
Functional Theory ◽  
Surface Filling

At room environment, all materials can be classified as insulators or metals or in-between semiconductors, by judging whether they are capable of conducting the flow of electrons. One can expect an insulator to convert into a metal and to remain in this state upon further compression, i.e., pressure-induced metallization. Some exceptions were reported recently in elementary metals such as all of the alkali metals and heavy alkaline earth metals (Ca, Sr, and Ba). Here we show that a compound of CLi4 becomes progressively less conductive and eventually insulating upon compression based on ab initio density-functional theory calculations. An unusual path with pressure is found for the phase transition from metal to semimetal, to semiconductor, and eventually to insulator. The Fermi surface filling parameter is used to describe such an antimetallization process.

scholarly journals Crystal structure of rare earth and group III nitride alloys by ab initio calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Maciej J. Winiarski ◽  
Dorota A. Kowalska
Keyword(s):  
Rare Earth ◽  
Density Functional ◽  
Metastable Phase ◽  
Rare Earth Ions ◽  
Ternary Alloys ◽  
Wurtzite Phase ◽  
Functional Theory ◽  
Group Iii ◽  
The Density Functional Theory ◽  
Group Iii Nitride

Abstract The ground state phases of ternary alloys of rare earth and group III nitride semiconductors have been investigated within the density functional theory. The most energetically favorable crystal phases among possible cubic and hexagonal structures, i.e., the rock salt, zinc blende, wurtzite, and hexagonal BN, were determined. The type of a unit cell and the lattice parameters of the materials are presented as a function of their composition. Furthermore, effects of strain on ground states of group III and rare earth nitride materials are discussed. The findings presented in this work discloses the wurtzite type materials as being stable with relatively low contents of rare earth elements. It is expected that the wurtzite phase will be very persistent only in the La-based systems. Nevertheless, the two-dimensional hexagonal atomic layers are revealed as being a metastable phase for all alloys studied. This finding supports the conclusion of previous experimental reports for Sc-doped GaN systems that the presence of rare earth ions in group III nitride materials leads to flattening of the wurtzite type layers.

High-performance III–VI monolayer transistors for flexible devices

2020 ◽  
Vol 22 (13) ◽  
pp. 7039-7047 ◽  
Author(s):  
Jianhui Chen ◽  
Shuchang Cai ◽  
Rui Xiong ◽  
Baisheng Sa ◽  
Cuilian Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Density Functional Theory ◽  
Quantum Transport ◽  
High Performance ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Device Performance ◽  
Functional Theory ◽  
Group Iii ◽  
Flexible Devices

The mechanical properties of group III–VI monolayers and sub-10 nm scale device performance of corresponding MOSFETs have been investigated by using density functional theory calculations as well as ab initio quantum transport simulations.

THEORETICAL EVIDENCE FOR UNUSUAL BONDING GEOMETRY AND PHASE TRANSITIONS OF Na ON Al(001)

1994 ◽  
Vol 01 (02n03) ◽  
pp. 213-219 ◽  
Author(s):  
C. STAMPFL ◽  
J. NEUGEBAUER ◽  
M. SCHEFFLER
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
Phase Transitions ◽  
Density Functional ◽  
Alkali Metals ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Island Formation ◽  
Low Concentration ◽  
Theoretical Evidence

We performed density-functional theory calculations for Na on Al(001) for various coverages from a very low concentration up to a monolayer. From the results we predict that for low coverages the Na atoms occupy on-surface hollow sites which is the stable geometry, but for higher coverages this is only metastable; the stable geometry is reached through a phase transition to a condensed c(2×2) structure where the Na atoms are in surface substitutional sites (contrary to previously suggested models). The mechanism which actuates the island formation with a substitutional geometry is described and the differences to the substitutional adsorption of alkali metals on Al(111) are discussed.

scholarly journals Anomalous doping effect in black phosphorene using first-principles calculations

2015 ◽  
Vol 17 (25) ◽  
pp. 16351-16358 ◽  
Author(s):  
Weiyang Yu ◽  
Zhili Zhu ◽  
Chun-Yao Niu ◽  
Chong Li ◽  
Jun-Hyung Cho ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Electronic Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Doping Effect ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Group Iii ◽  
Black Phosphorene

Using first-principles density functional theory calculations, we investigate the geometries, electronic structures, and thermodynamic stabilities of substitutionally doped phosphorene sheets with group III, IV, V, and VI elements.

scholarly journals Effect of mechanical strain on the Dirac surface states in the (0001) surface and cohesive energy of the topological insulator Bi2Se3

2021 ◽  
Author(s):  
Soumendra Kumar Das ◽  
Prahallad Padhan
Keyword(s):  
Density Functional Theory ◽  
Topological Insulator ◽  
First Principles ◽  
Cohesive Energy ◽  
Density Functional ◽  
Dirac Point ◽  
Mechanical Strain ◽  
Surface States ◽  
Density Functional Theory Calculations ◽  
Functional Theory

The band gap (Eg) engineering and Dirac point tuning of the (0001) surface of 8QLs (quintuple layers) thick Bi2Se3 slab are explored using the first-principles density functional theory calculations by...

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