Enhanced vibronic interaction caused by local lattice symmetry lowering in the (Fe, Mg)As2ternary system

2018 ◽  
Vol 123 (16) ◽  
pp. 161557
Author(s):  
A. Pishtshev ◽  
P. Rubin
Keyword(s):  
Vibronic Interaction ◽  
Lattice Symmetry ◽  
Local Lattice

Nuclear Magnetic Resonance of Amorphous Alloys CuxZr100-x(40≦x≦60)

1982 ◽  
Vol 37 (9) ◽  
pp. 1030-1034 ◽  
Author(s):  
J. Abart ◽  
W. Socher ◽  
J. Voitländer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Amorphous Alloys ◽  
Knight Shift ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
Lattice Symmetry ◽  
Local Lattice ◽  
Nuclear Magnetic

Abstract91Zr-and 63Cu-NMR measurements of the amorphous alloys CuxZr100-x(40≦x≦60) are reported. By comparison of the experimental quadrupole disturbed spectra with simulated spectra of the amorphous alloys a short range order can be deduced, which is similar to the local lattice symmetry of the corresponding crystalline compounds. Furthermore the Knight shift of both nuclei in the alloys could be determined.

Local lattice symmetry of spin-glass and antiferromagnetic URh2Ge2

2004 ◽  
Vol 272-276 ◽  
pp. 941-942 ◽  
Author(s):  
C.H. Booth ◽  
S.-W. Han ◽  
S. Süllow ◽  
J.A. Mydosh
Keyword(s):  
Spin Glass ◽  
Lattice Symmetry ◽  
Local Lattice

Computer Indexing of Electron Diffraction Patterns Including the Effects of Lattice Symmetry

1977 ◽  
Vol 35 ◽  
pp. 22-23
Author(s):  
J. S. Lally ◽  
R. J. Lee
Keyword(s):  
Electron Diffraction ◽  
Zone Axis ◽  
Crystal Thickness ◽  
Double Diffraction ◽  
Automated Method ◽  
Lattice Symmetry ◽  
Intensity Calculations ◽  
Unknown Structure ◽  
Diffraction Patterns ◽  
Orientation Parameters

In the 50 year period since the discovery of electron diffraction from crystals there has been much theoretical effort devoted to the calculation of diffracted intensities as a function of crystal thickness, orientation, and structure. However, in many applications of electron diffraction what is required is a simple identification of an unknown structure when some of the shape and orientation parameters required for intensity calculations are not known. In these circumstances an automated method is needed to solve diffraction patterns obtained near crystal zone axis directions that includes the effects of systematic absences of reflections due to lattice symmetry effects and additional reflections due to double diffraction processes.Two programs have been developed to enable relatively inexperienced microscopists to identify unknown crystals from diffraction patterns. Before indexing any given electron diffraction pattern, a set of possible crystal structures must be selected for comparison against the unknown.

Strain measurement in In0.2Ga0.8As/GaAs quantum wires by convergent beam electron diffraction

1995 ◽  
Vol 53 ◽  
pp. 444-445
Author(s):  
S. Hillyard ◽  
Y.-P. Chen ◽  
J.D. Reed ◽  
W.J. Schaff ◽  
L.F. Eastman ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Semiconductor Lasers ◽  
Quantum Wire ◽  
Quantum Wires ◽  
Convergent Beam Electron Diffraction ◽  
Zero Order ◽  
Beam Electron ◽  
Local Lattice ◽  
Device Applications ◽  
Convergent Beam

The positions of high-order Laue zone (HOLZ) lines in the zero order disc of convergent beam electron diffraction (CBED) patterns are extremely sensitive to local lattice parameters. With proper care, these can be measured to a level of one part in 104 in nanometer sized areas. Recent upgrades to the Cornell UHV STEM have made energy filtered CBED possible with a slow scan CCD, and this technique has been applied to the measurement of strain in In0.2Ga0.8 As wires.Semiconductor quantum wire structures have attracted much interest for potential device applications. For example, semiconductor lasers with quantum wires should exhibit an improvement in performance over quantum well counterparts. Strained quantum wires are expected to have even better performance. However, not much is known about the true behavior of strain in actual structures, a parameter critical to their performance.

The limits of strain and lattice parameter measurements by CBED

1989 ◽  
Vol 47 ◽  
pp. 518-519
Author(s):  
Hamish L. Fraser
Keyword(s):  
Electron Beam ◽  
Mirror Symmetry ◽  
Local Symmetry ◽  
Lattice Parameter ◽  
Growth Direction ◽  
Surface Relaxation ◽  
Strained Layer ◽  
Axis Parallel ◽  
Local Lattice ◽  
Strained Layer Superlattice

The topic of strain and lattice parameter measurements using CBED is discussed by reference to several examples. In this paper, only one of these examples is referenced because of the limitation of length. In this technique, scattering in the higher order Laue zones is used to determine local lattice parameters. Work (e.g. 1) has concentrated on a model strained-layer superlattice, namely Si/Gex-Si1-x. In bulk samples, the strain is expected to be tetragonal in nature with the unique axis parallel to [100], the growth direction. When CBED patterns are recorded from the alloy epi-layers, the symmetries exhibited by the patterns are not tetragonal, but are in fact distorted from this to lower symmetries. The spatial variation of the distortion close to a strained-layer interface has been assessed. This is most readily noted by consideration of Fig. 1(a-c), which show enlargements of CBED patterns for various locations and compositions of Ge. Thus, Fig. 1(a) was obtained with the electron beam positioned in the center of a 5Ge epilayer and the distortion is consistent with an orthorhombic distortion. When the beam is situated at about 150 nm from the interface, the same part of the CBED pattern is shown in Fig. 1(b); clearly, the symmetry exhibited by the mirror planes in Fig. 1 is broken. Finally, when the electron beam is positioned in the center of a 10Ge epilayer, the CBED pattern yields the result shown in Fig. 1(c). In this case, the break in the mirror symmetry is independent of distance form the heterointerface, as might be expected from the increase in the mismatch between 5 and 10%Ge, i.e. 0.2 to 0.4%, respectively. From computer simulation, Fig.2, the apparent monocline distortion corresponding to the 5Ge epilayer is quantified as a100 = 0.5443 nm, a010 = 0.5429 nm and a001 = 0.5440 nm (all ± 0.0001 nm), and α = β = 90°, γ = 89.96 ± 0.02°. These local symmetry changes are most likely due to surface relaxation phenomena.

Local Lattice Distortion and Chemical Short Range Order in High Entropy Alloys

2020 ◽  
Author(s):  
Yuan-Yuan Tan ◽  
Ming-Yao Su ◽  
Zhou-Can Xie ◽  
Zhong-Jun Chen ◽  
Yu Gong ◽  
...  
Keyword(s):  
Short Range ◽  
Short Range Order ◽  
Lattice Distortion ◽  
Range Order ◽  
High Entropy Alloys ◽  
Local Lattice Distortion ◽  
High Entropy ◽  
Local Lattice

scholarly journals Lattice symmetry and emergence of antiferromagnetic quantum Hall states

2021 ◽  
Vol 103 (15) ◽  
Author(s):  
Morad Ebrahimkhas ◽  
Mohsen Hafez-Torbati ◽  
Walter Hofstetter
Keyword(s):  
Quantum Hall ◽  
Quantum Hall States ◽  
Lattice Symmetry ◽  
Hall States

scholarly journals Three dimensional band-filling control of complex oxides triggered by interfacial electron transfer

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Meng Meng ◽  
Yuanwei Sun ◽  
Yuehui Li ◽  
Qichang An ◽  
Zhenzhen Wang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Field Effect ◽  
Essential Role ◽  
Field Effect Transistors ◽  
Three Dimensional ◽  
Complex Oxides ◽  
Band Filling ◽  
Local Lattice ◽  
Oxygen Migration ◽  
Oxide Heterostructure

AbstractThe d-band-filling of transition metals in complex oxides plays an essential role in determining their structural, electronic and magnetic properties. Traditionally, at the oxide heterointerface, band-filling control has been achieved via electrostatic modification in the structure of field-effect transistors or electron transfer, which is limited to the quasi-two-dimension at the interface. Here we report a three-dimensional (3D) band-filling control by changing the local lattice coordination in a designed oxide heterostructure. At the LaCoO3/LaTiO3 heterointerface, due to the Fermi level mismatch, electrons transfer from LaTiO3 to LaCoO3. This triggers destabilisation of the CoO6 octahedrons, i.e. the formation of lattice configurations with a reduced Co valence. The associated oxygen migration results in the 3D topotactic phase transition of LaCoO3. Tuned by the thickness of LaTiO3, different crystalline phases and band-fillings of Co occur, leading to the emergence of different magnetic ground states.

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