Electronic structure of Ti-doped Sr4Sc2Fe2As2O6 as a possible parent phase for the new FeAs superconductors

Open Physics ◽  
2010 ◽  
Vol 8 (3) ◽  
Author(s):  
Igor Shein ◽  
Alexander Ivanovskii
Keyword(s):  
Electronic Structure ◽  
Fermi Level ◽  
Electronic Properties ◽  
Parent Phase ◽  
Oxide Phase ◽  
Sharp Contrast ◽  
First Principle ◽  
Ti Doping ◽  
Feas Based Superconductors ◽  
Feas Superconductors

AbstractFirst principle FLAPW-GGA calculations have been performed with the purpose to understand the effect of Ti-doping on the electronic properties for the newly discovered tetragonal iron arsenide-oxide Sr4Sc2Fe2As2O6 (abbreviated as FeAs42226) as the possible parent phase for the new FeAs superconductors. Our results show that the insertion of Ti into Sc sublattice of this five-component iron arsenide-oxide phase leads to the resolute change of electronic structure of FeAs42226. Namely, the insulating oxygen-containing [Sr4Sc2O6] blocks in Ti-doped FeAs42226 became conducting, and this differs essentially from the known picture for all others FeAs superconductors where the conducting [Fe2As2] blocks are alternated with insulating blocks. Moreover in sharp contrast with FeAs-based superconductors with Fe 3d bands near the Fermi level, for Ti-doped FeAs42226 in this region the Ti 3d states are dominated, whereas the Fe 3d states are suppressed.

PRESSURE EFFECT ON THE MgB2 ELECTRON STRUCTURE FROM FIRST PRINCIPLE CALCULATIONS

2007 ◽  
Vol 21 (16) ◽  
pp. 2793-2803
Author(s):  
LI CHEN
Keyword(s):  
Electronic Structure ◽  
Fermi Level ◽  
Density Of States ◽  
Electron Distribution ◽  
Pressure Effect ◽  
The Other ◽  
First Principle ◽  
First Principle Calculations ◽  
Bonding Property ◽  
Density Population

The electronic structure of MgB 2 with different lattice parameters, which represents the influence of pressure, has been studied from HF calculation. It has been found that the density of states at the Fermi level decreases with the decrease in lattice constant, which implies that the pressure can reduce the superconductivity of MgB 2. It was also found that more electrons are introduced from the Mg layer to the B layer with increasing pressure, resulting in the number of holes on the B layer being reduced, thus reducing superconductivity. The electron density population at different pressures clearly shows that the triangle-shaped electron distribution in the B plane, extended along the B–B bonds, indicates the typical sp2 orbitals. On the other hand, there is no covalency feature between Mg and B atoms, indicating the ionic bonding property between Mg and B layers.

Atomic-Scale Imaging

2021 ◽  
pp. 187-234
Author(s):  
C. Julian Chen
Keyword(s):  
Electronic Structure ◽  
Transition Metal ◽  
Fermi Level ◽  
Electronic States ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
First Principle ◽  
Spin Polarized ◽  
Quantitative Explanation

This chapter discusses the imaging mechanism of STM and AFM at the atomic scale. Experimental facts show that at atomic resolution, tip electronic states play a key role. Analytic theoretical treatments provide quantitative explanation of the effect of the tip electronic states. On transition-metal tips, first-principle studies unanimously show that d-type tip electronic states dominate the Fermi-level DOS. First-principle studies of the combined tip-sample systems show that for both STM and AFM, the p- and d-type tip electronic states are the keys to understanding the atomic-scale images. The case of spin-polarized STM and the chemical identification of surface atoms are also discussed in terms of tip electronic structure. The chapter concludes with discussions of experimental verifications of the reciprocity principle: at atomic resolution, the role of tip electronic states and the sample electronic states are interchangeable.

ELECTRONIC STRUCTURE OF ASSEMBLED CLUSTERS WITHIN THE STABILIZED JELLIUM MODEL

1996 ◽  
Vol 03 (01) ◽  
pp. 1001-1006
Author(s):  
HENRIK GRÖNBECK ◽  
ARNE ROSÉN
Keyword(s):  
Electronic Structure ◽  
Binding Energy ◽  
Fermi Level ◽  
Electronic Properties ◽  
Closed Shell ◽  
Building Blocks ◽  
Jellium Model

The electronic structure of assembled closed shell clusters have been analyzed using a spherical, stabilized jellium description of the clusters. The effects of including stabilization terms to the jellium model were investigated by calculating the properties of cluster dimers, (Na20)2 and ( Cu 20)2. In addition, the electronic properties of a material consisting of closed shell Al 12X clusters, where X is C or Si, were investigated using a model of six clusters. The large gap at the Fermi level present for the building blocks was also found to appear for the cluster-assembled material. The binding energy of the clusters in the cluster-assembled material was compared with that of an atomic Al lattice.

Electronic Structure of δ-Pu and PuCoGa5 from Photoemission and the Mixed Level Model

2003 ◽  
Vol 802 ◽  
Author(s):  
John J. Joyce ◽  
John M. Wills ◽  
Tomasz Durakiewicz ◽  
Elzbieta Guziewicz ◽  
Martin T. Butterfield ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Fermi Level ◽  
Electronic Properties ◽  
Excellent Agreement ◽  
Fermi Energy ◽  
Photoelectron Spectroscopy ◽  
Spectral Intensity ◽  
Δ Phase ◽  
Level Model ◽  
Photoemission Data

ABSTRACTThe electronic structure of δ-phase Pu metal and the Pu-based superconductor PuCoGa5 is explored using photoelectron spectroscopy and a novel theoretical scheme. Excellent agreement between calculation and experiment defines a path forward for understanding electronic structure aspects of Pu-based materials. The photoemission results show two separate regions of 5f electron spectral intensity, one at the Fermi energy and another centered 1.2 eV below the Fermi level. A comparison is made between the photoemission data and five computational schemes for δ-Pu. The results for δ-Pu and PuCoGa5 indicate 5f electron behavior on the threshold between localized and itinerant and a broader framework for understanding the fundamental electronic properties of the Pu 5f levels in general within two configurations, one localized and one itinerant.

Ab Initio Calculations of Electronic Properties of Al Doped LaMnO3 Perovskite Manganites

2015 ◽  
Vol 754-755 ◽  
pp. 762-765
Author(s):  
A. Chik ◽  
S. Saad ◽  
R.M. Zaki ◽  
F. Che Pa ◽  
C.K. Yeoh
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Fermi Level ◽  
Ab Initio ◽  
Electronic Properties ◽  
Density Functional ◽  
Perovskite Manganites ◽  
Functional Theory ◽  
Temperature Range ◽  
Energy Approximation

The electronic structure of the perovskite manganites LaMnO3 and La2/3 Al1/3 MnO3 was presented. The calculations were made within density functional theory (DFT) and PBE exchange correlations energy approximation. It was found that inclusion of Al dopants add additional states near the Fermi level and decreasing the resistivity values for all temperature range.

Structural and Electronic Structure of SnO2 by the First-Principle Study

2012 ◽  
Vol 725 ◽  
pp. 265-268 ◽  
Author(s):  
Minoru Oshima ◽  
Kenji Yoshino
Keyword(s):  
Electronic Structure ◽  
Electronic Properties ◽  
Valence Band ◽  
Conduction Band ◽  
Valence Band Maximum ◽  
First Principle ◽  
Band Maximum ◽  
First Principle Calculations ◽  
Calculation Results ◽  
Good Agreement

We performed first-principle calculations to investigate the effects of F, Cl and Sb impurities on the electronic properties of SnO2. We obtained, firstly, the electronic structure of SnO2, a valence band maximum of SnO2is an O 2p orbital and a conduction band minimum was an antibonding Sn 5s and O 2p orbitals dominantly. Secondly, those impurites doped SnO2was obtained the electronic structure. The F, Cl and Sb impurities as n-type dopants exhibited shallow donors. This calculation results were in good agreement with our prvious experiment that we obtained the low resistivity SnO2.

Structural and electronic properties of InPBi alloys

2014 ◽  
Vol 28 (17) ◽  
pp. 1450140 ◽  
Author(s):  
Xianlong Zhang ◽  
Pengfei Lu ◽  
Lihong Han ◽  
Zhongyuan Yu ◽  
Jun Chen ◽  
...  
Keyword(s):  
Fermi Level ◽  
Electronic Properties ◽  
Formation Energy ◽  
Covalent Bonding ◽  
First Principle ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Biaxial Strain ◽  
First Principle Calculations ◽  
Structural And Electronic Properties

First-principle calculations have been performed to systematically investigate structural and electronic properties of InPBi alloys. The formation energy of seven different configurations is studied. The strength of covalent bonding largely depends on the strong s–p hybridization among In -5s, P -3p and Bi -6p states. The band gap of InPBi shrinks clearly with the increasing Bi concentration and the band edge shifts when spin-orbit coupling (SOC) is considered. The insertion of Bi atom leads to hybridization of In / P / Bi p states which contributes a lot around Fermi level. In addition, our results show that the biaxial strain is an effective method to tune the electronic properties of the system.

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