First Principles Calculation of Electrical Conductivity and Giant Magnetoresistance of ColCu Multilayers

1995 ◽  
Vol 384 ◽  
Author(s):  
W. H. Butler ◽  
X.-G. Zhang ◽  
D. M. C. Nicholson ◽  
J. M. Maclaren
Keyword(s):  
Electrical Conductivity ◽  
Green Function ◽  
First Principles ◽  
Density Functional ◽  
Giant Magnetoresistance ◽  
Local Density ◽  
First Principles Calculation ◽  
Kubo Formula ◽  
Minority Spin ◽  
Interfacial Scattering

ABSTRACTWe show that the Kubo formula can be used to calculate the non-local electrical conductivity of layered systems from first principles. We use the Layer Korringa Kohn Rostoker method to calculate the electronic structure and the Green function of Co/Cu/Co trilayers within the local density approximation to density functional theory. This Green function is used to calculate the conductivity through the Kubo formula for both majority and minority spins and for alignment and anti-alignment of the Co moments on either side of the Cu spacer layer. This allows us to determine the giant magnetoresistance from first principles. We investigate three possibilities for the scattering in Co/Cu/Co: (1) equal electron lifetimes for Cu, majority spin Co, and minority spin Co, (2) equal electron lifetimes for majority and minority Co, weaker scattering in Cu and spin dependent interfacial scattering, (3) electron lifetimes for majority and minority spin cobalt proportional to their Fermi energy densities of states and spin dependent interfacial scattering.

scholarly journals Structural and Electronic Properties of Orthorhombic Phase Bi2Se3 Based On First-Principles Study

2019 ◽  
Vol 16 (2) ◽  
pp. 77 ◽  
Author(s):  
Muhammad Zamir Mohyedin ◽  
Afiq Radzwan ◽  
Mohammad Fariz Mohamad Taib ◽  
Rosnah Zakaria ◽  
Nor Kartini Jaafar ◽  
...  
Keyword(s):  
Electronic Properties ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Computer Code ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Exchange Correlation ◽  
Percentage Difference ◽  
Structural And Electronic Properties

Bi2Se3 is one of the promising materials in thermoelectric devices and very useful out of environmental concern due to its efficiency to perform at room temperature. Based on the first-principles calculation of density functional theory (DFT) by using CASTEP computer code, structural and electronic properties of Bi2Se3 were investigated. The calculation is conducted within the exchange-correlation of local density approximation (LDA) and generalized gradient approximation within the revision of Perdew-Burke-Ernzerhof (GGA-PBE) functional. It was found that the results are consistent with previous works of theoretical study with small percentage difference. LDA exchange-correlation functional method is more accurate and have a better agreement than GGA-PBE to describe the structural properties of Bi2Se3 which consist of lattice parameters. LDA functional also shown more accurate electronic structure of Bi2Se3 that consist of band structure and density of states (DOS) which consistent with most previous theoretical works with small percentage difference. This study proves the reliability of CASTEP computer code and show LDA exchange-correlation functional is more accurate in describing the nature of Bi2Se3 compared to the other functionals.

scholarly journals Insight into Physical and Thermodynamic Properties of X3Ir (X = Ti, V, Cr, Nb and Mo) Compounds Influenced by Refractory Elements: A First-Principles Calculation

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 104 ◽  
Author(s):  
Dong Chen ◽  
Jiwei Geng ◽  
Yi Wu ◽  
Mingliang Wang ◽  
Cunjuan Xia
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
First Principles Calculation ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Debye Temperatures ◽  
Experimental Parameters ◽  
Experimental Values

The effects of refractory metals on physical and thermodynamic properties of X3Ir (X = Ti, V, Cr, Nb and Mo) compounds were investigated using local density approximation (LDA) and generalized gradient approximation (GGA) methods within the first-principles calculations based on density functional theory. The optimized lattice parameters were both in good compliance with the experimental parameters. The GGA method could achieve an improved structural optimization compared to the LDA method, and thus was utilized to predict the elastic, thermodynamic and electronic properties of X3Ir (X = Ti, V, Cr, Nb and Mo) compounds. The calculated mechanical properties (i.e., elastic constants, elastic moduli and elastic anisotropic behaviors) were rationalized and discussed in these intermetallics. For instance, the derived bulk moduli exhibited the sequence of Ti3Ir < Nb3Ir < V3Ir < Cr3Ir < Mo3Ir. This behavior was discussed in terms of the volume of unit cell and electron density. Furthermore, Debye temperatures were derived and were found to show good consistency with the experimental values, indicating the precision of our calculations. Finally, the electronic structures were analyzed to explain the ductile essences in the iridium compounds.

First-principles Calculation of Electron Mobilities in Ultrathin SOI MOSFETs

2004 ◽  
Vol 829 ◽  
Author(s):  
Matthew H. Evans ◽  
Xiaoguang Zhang ◽  
John D. Joannopoulos ◽  
Sokrates T. Pantelides
Keyword(s):  
Electron Transport ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Computational Effort ◽  
Silicon On Insulator ◽  
Atomic Scale ◽  
First Principles Calculation ◽  
Oxide Interface ◽  
Ultrathin Soi

ABSTRACTUltrathin silicon-on-insulator (UTSOI) technology1 has emerged as a key candidate for sub-100nm gate length CMOS devices. Recent experiments have characterized MOSFETs with silicon channels as thin as 1nm (four atomic layers of silicon),2,3 and found them to be well-behaved electrically. Quantum effects are important to the electron transport in such devices, and the penetration of the electron wavefunction into the gate oxide introduces new scattering mechanisms. We introduce here a novel method for first-principles calculation of electron mobilities in ultrathin SOI channels, including surface roughness and defect scattering. The electronic structure and scattering potentials are calculated with Density Functional Theory in the Local Density Approximation (DFT-LDA), and the mobility is calculated through Green's functions. The method requires little computational effort beyond that of the DFT-LDA calculations, and allows the calculation of temperature- and carrier concentration-dependent mobilities. Since the silicon-oxide interface is treated at the atomic-scale, the mobility contributions of different defects (e.g. suboxide bonds, oxide protrusions) and impurities (e.g. nitrogen, hydrogen) can be calculated separately, giving a precise physical picture of channel electron transport.

First principles calculation of thermo-mechanical properties of thoria using Quantum ESPRESSO

2016 ◽  
Vol 05 (02) ◽  
pp. 1650008 ◽  
Author(s):  
Linu Malakkal ◽  
Barbara Szpunar ◽  
Juan Carlos Zuniga ◽  
Ravi Kiran Siripurapu ◽  
Jerzy A. Szpunar
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Harmonic Approximation ◽  
First Principles Calculation ◽  
Thorium Dioxide ◽  
Phonon Contribution ◽  
Quantum Espresso

In this work, we have used Quantum ESPRESSO (QE), an open source first principles code, based on density-functional theory, plane waves, and pseudopotentials, along with quasi-harmonic approximation (QHA) to calculate the thermo-mechanical properties of thorium dioxide (ThO[Formula: see text]. Using Python programming language, our group developed qe-nipy-advanced, an interface to QE, which can evaluate the structural and thermo-mechanical properties of materials. We predicted the phonon contribution to thermal conductivity ([Formula: see text] using the Slack model. We performed the calculations within local density approximation (LDA) and generalized gradient approximation (GGA) with the recently proposed version for solids (PBEsol). We employed a Monkhorst-Pack [Formula: see text] k-points mesh in reciprocal space with a plane wave cut-off energy of 150 Ry to obtain the convergence of the structure. We calculated the dynamical matrices of the lattice on a [Formula: see text] mesh. We have predicted the heat capacity, thermal expansion and the phonon contribution to thermal conductivity, as a function of temperature up to 1400[Formula: see text]K, and compared them with the previous work and known experimental results.

First Principles Calculation of Residual Resistivity

1991 ◽  
Vol 253 ◽  
Author(s):  
D. M. Nicholson ◽  
R. H. Brown ◽  
W. H. Butler ◽  
H. Yang ◽  
J. W. Swihart ◽  
...  
Keyword(s):  
Multiple Scattering ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Mean Free Path ◽  
Residual Resistivity ◽  
First Principles Calculation ◽  
Functional Theory ◽  
Disordered Alloys ◽  
Random Alloys

ABSTRACTThe list of physical properties which are important in the design of materials and which are routinely calculated from first principles within the local density approximation to density functional theory is continually growing. In this paper we discuss the application of multiple scattering theory to the calculation of the residual resistivity of disordered alloys. Progress has been made on two fronts. First, the coherent potential approximation for the resistivity, which sums to all orders a limited set of multiple scattering diagrams, has given resistivities in agreement with experiment for alloys where the site occupation is roughly random. Second, the linearized KKR was used to evaluate the Kubo formula for several large configurations of atoms and obtain the resistivity with all multiple scattering paths included. This method is not limited to random alloys, but can be applied to short range ordered and amorphous alloys provided the resistivity is high enough to limit the mean free path to a single unit cell.

Magnetic Properties of Embedded Rh Clusters in Ni Matrix

1995 ◽  
Vol 384 ◽  
Author(s):  
Zhi-Qiang Li ◽  
Yuichi Hashi ◽  
Jing-Zhi Yu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Functional Formalism ◽  
Rhodium Clusters ◽  
Spin Polarized ◽  
Local Density Functional

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.

Pros and cons of time-dependent hybrid density functional approach to optical spectra of solids: a case study of CeO2

2021 ◽  
Author(s):  
Huai-Yang Sun ◽  
Shuo-Xue Li ◽  
Hong Jiang
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Computational Cost ◽  
Optical Spectra ◽  
First Principles Calculation ◽  
Many Body ◽  
Many Body Perturbation Theory ◽  
Pros And Cons ◽  
Hybrid Density Functional

Prediction of optical spectra of complex solids remains a great challenge for first-principles calculation due to the huge computational cost of the state-of-the-art many-body perturbation theory based GW-Bethe Salpeter equation...

Structural, elastic and thermodynamic properties of A15-type compounds V3X (X = Ir, Pt and Au) from first-principles calculations

2016 ◽  
Vol 30 (35) ◽  
pp. 1650414 ◽  
Author(s):  
Mingliang Wang ◽  
Zhe Chen ◽  
Dong Chen ◽  
Cunjuan Xia ◽  
Yi Wu
Keyword(s):  
Thermodynamic Properties ◽  
Debye Temperature ◽  
First Principles ◽  
Density Functional ◽  
Coefficient Of Thermal Expansion ◽  
Local Density ◽  
Debye Model ◽  
First Principles Calculations ◽  
Generalized Gradient ◽  
Experimental Values

The structural, elastic and thermodynamic properties of the A15 structure V3Ir, V3Pt and V3Au were studied using first-principles calculations based on the density functional theory (DFT) within generalized gradient approximation (GGA) and local density approximation (LDA) methods. The results have shown that both GGA and LDA methods can process the structural optimization in good agreement with the available experimental parameters in the compounds. Furthermore, the elastic properties and Debye temperatures estimated by LDA method are typically larger than the GGA methods. However, the GGA methods can make better prediction with the experimental values of Debye temperature in V3Ir, V3Pt and V3Au, signifying the precision of the calculating work. Based on the E–V data derived from the GGA method, the variations of the Debye temperature, coefficient of thermal expansion and heat capacity under pressure ranging from 0 GPa to 50 GPa and at temperature ranging from 0 K to 1500 K were obtained and analyzed for all compounds using the quasi-harmonic Debye model.

scholarly journals Strain Conditions for the Inverse Heusler Type Fully Compensated Spin-Gapless Semiconductor Ti2MnAl: A First-Principles Study

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2091 ◽  
Author(s):  
Tie Yang ◽  
Liyu Hao ◽  
Rabah Khenata ◽  
Xiaotian Wang
Keyword(s):  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Study ◽  
Debye Model ◽  
Pressure Effects ◽  
First Principles Calculation ◽  
Strain Condition ◽  
Functional Theory ◽  
Future Work

In this work, we systematically studied the structural, electronic, magnetic, mechanical and thermodynamic properties of the fully compensated spin-gapless inverse Heusler Ti2MnAl compound under pressure strain condition by applying the first-principles calculation based on density functional theory and the quasi-harmonic Debye model. The obtained structural, electronic and magnetic behaviors without pressure are well consistent with previous studies. It is found that the spin-gapless characteristic is destroyed at 20 GPa and then restored with further increase in pressure. While, the fully compensated ferromagnetism shows a better resistance against the pressure up to 30 GPa and then becomes to non-magnetism at higher pressure. Tetragonal distortion has also been investigated and it is found the spin-gapless property is only destroyed when c/a is less than 1 at 95% volume. Three independent elastic constants and various moduli have been calculated and they all show increasing tendency with pressure increase. Additionally, the pressure effects on the thermodynamic properties under different temperature have been studied, including the normalized volume, thermal expansion coefficient, heat capacity at constant volume, Grüneisen constant and Debye temperature. Overall, this theoretical study presents a detailed analysis of the physical properties’ variation under strain condition from different aspects on Ti2MnAl and, thus, can provide a helpful reference for the future work and even inspire some new studies and lead to some insight on the application of this material.

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