scholarly journals Symmetry rules shaping spin-orbital textures in surface states

2017 ◽  
Vol 95 (24) ◽  
Author(s):  
Kenneth Gotlieb ◽  
Zhenglu Li ◽  
Chiu-Yun Lin ◽  
Chris Jozwiak ◽  
Ji Hoon Ryoo ◽  
...  
Keyword(s):  
Surface States ◽  
Spin Orbital ◽  
Symmetry Rules

scholarly journals A first-principles investigation of band inversion in topologically nontrivial Na2AgX (X= As, Sb and Bi) full Heusler compounds

2021 ◽  
Vol 24 (2) ◽  
pp. 23602
Author(s):  
A. Boughena ◽  
S. Benalia ◽  
O. Cheref ◽  
N. Bettahar ◽  
D. Rached
Keyword(s):  
First Principles ◽  
Surface States ◽  
Metallic Surface ◽  
Full Potential ◽  
Topological Order ◽  
Heusler Compounds ◽  
Spin Orbital ◽  
Lmto Method ◽  
Potential Applications ◽  
Full Heusler

Topological nontrivial nature are the latest phases to be discovered in condensed matter physics with insulating bulk band gaps and topologically protected metallic surface states; they are one of the current hot topics because of their unique properties and potential applications. In this paper, we have highlighted a first-principles study of the structural stability and electronic behavior of the Na2AgX (X = As, Sb and Bi) full Heusler compounds, using the Full-Potential Linear Muffin-Tin Orbital (FP-LMTO) method. We have originated that the Hg2CuTi structure is appropriate in all studied materials. The negative values of the calculated formation energies mean that these compounds are energetically stable. The band structure is studied for the two cases relating the existence and the absence of spin-orbital couplings, where all materials are shown to be topologically non-trivial compounds. Spin orbital couplings were noticed to have no significant effect on the electronic properties such as the topological order.

scholarly journals Weyl-like points from band inversions of spin-polarised surface states in NbGeSb

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
I. Marković ◽  
C. A. Hooley ◽  
O. J. Clark ◽  
F. Mazzola ◽  
M. D. Watson ◽  
...  
Keyword(s):  
Mirror Symmetry ◽  
Density Functional ◽  
Three Dimensional ◽  
Surface States ◽  
Nodal Line ◽  
Surface Band ◽  
Spin Orbital ◽  
Band Inversion ◽  
Topological Surface ◽  
Symmetry Protected

AbstractBand inversions are key to stabilising a variety of novel electronic states in solids, from topological surface states to the formation of symmetry-protected three-dimensional Dirac and Weyl points and nodal-line semimetals. Here, we create a band inversion not of bulk states, but rather between manifolds of surface states. We realise this by aliovalent substitution of Nb for Zr and Sb for S in the ZrSiS family of nonsymmorphic semimetals. Using angle-resolved photoemission and density-functional theory, we show how two pairs of surface states, known from ZrSiS, are driven to intersect each other near the Fermi level in NbGeSb, and to develop pronounced spin splittings. We demonstrate how mirror symmetry leads to protected crossing points in the resulting spin-orbital entangled surface band structure, thereby stabilising surface state analogues of three-dimensional Weyl points. More generally, our observations suggest new opportunities for engineering topologically and symmetry-protected states via band inversions of surface states.

Interfacial Hydroxyl Promotes the Reduction of 4 Nitrophenol by Ag-Based Catalysts Confined in Dendritic Mesoporous Silica Nanospheres

2020 ◽  
Author(s):  
Xiao-Dan Hu ◽  
Bingqian Shan ◽  
Ran Tao ◽  
Taiqun Yang ◽  
Kun Zhang
Keyword(s):  
Mesoporous Silica ◽  
Surface States ◽  
Selective Reduction ◽  
Solid Material ◽  
Silica Nanospheres ◽  
Band Theory ◽  
Spin Orbital ◽  
Static Electron ◽  
Intermediate Surface ◽  
Mesoporous Silica Nanospheres

Surface states—the electronic states emerging as a solid material terminates at a surface—are usually vulnerable to contaminations and defects. This fundamental limitation has prohibited systematic studies of the potential role of surface states in surface reactions and catalysis, especially in more realistic environments. We use the selective reduction of 4-Nitrophenol on silver-covered dendritic mesoporous silica nanospheres (DMSNs) as a prototype example, and show that the dynamic intermediate surface states (DISS) spatially formed by spin orbital coupling (SOC) in singly hydrated hydroxyl complex can significantly enhance the adsorption energy of both 4-Nitrophenol and BH4- anions, by promoting different directions of static electron transfer. The concept of DISS as an electron bath may lead to new design principles beyond the conventional d-band theory of heterogeneous catalysis.

Strong Spin-Orbital Coupling and Robust Surface States in SrirO 3 Films: Confirmation by Increasing Lattice Disorder

2021 ◽  
Author(s):  
Changan Wang ◽  
Ching-Hao Chang ◽  
Madhav Prasad Ghimire ◽  
Min Zeng ◽  
Ping-Chun Wu ◽  
...  
Keyword(s):  
Surface States ◽  
Spin Orbital ◽  
Lattice Disorder ◽  
Spin Orbital Coupling ◽  
Strong Spin

Entanglement and quantum phase transition in topological insulators

2019 ◽  
Vol 33 (32) ◽  
pp. 1950394
Author(s):  
Anant Vijay Varma ◽  
Anvesh Raja Kovela ◽  
Prasanta K. Panigrahi ◽  
Bhavesh Chouhan
Keyword(s):  
Phase Transition ◽  
Hilbert Space ◽  
Quantum Phase Transition ◽  
Surface States ◽  
Dimensional Subspace ◽  
Quantum Phase ◽  
Entangled States ◽  
Spin Orbital ◽  
Orbital Space ◽  
Qubit States

Presence of entangled states is explicitly shown in a topological insulator (TI) [Formula: see text]. The surface and bulk state are found to have different structures of entanglement. The surface states live as maximally entangled states in a four-dimensional subspace of total Hilbert space (spin, orbital, space). However, bulk states are entangled in the whole Hilbert space. Bulk states are found to be entangled maximally by controlled injection of electrons with momentum only along the [Formula: see text]-direction. At quantum phase transition (QPT) point, both states become maximally entangled two qubit states.

Interfacial Hydroxyl Promotes the Reduction of 4 Nitrophenol by Ag-Based Catalysts Confined in Dendritic Mesoporous Silica Nanospheres

2020 ◽  
Author(s):  
Xiao-Dan Hu ◽  
Bingqian Shan ◽  
Ran Tao ◽  
Taiqun Yang ◽  
Kun Zhang
Keyword(s):  
Mesoporous Silica ◽  
Surface States ◽  
Selective Reduction ◽  
Solid Material ◽  
Silica Nanospheres ◽  
Band Theory ◽  
Spin Orbital ◽  
Static Electron ◽  
Intermediate Surface ◽  
Mesoporous Silica Nanospheres

Surface states—the electronic states emerging as a solid material terminates at a surface—are usually vulnerable to contaminations and defects. This fundamental limitation has prohibited systematic studies of the potential role of surface states in surface reactions and catalysis, especially in more realistic environments. We use the selective reduction of 4-Nitrophenol on silver-covered dendritic mesoporous silica nanospheres (DMSNs) as a prototype example, and show that the dynamic intermediate surface states (DISS) spatially formed by spin orbital coupling (SOC) in singly hydrated hydroxyl complex can significantly enhance the adsorption energy of both 4-Nitrophenol and BH4- anions, by promoting different directions of static electron transfer. The concept of DISS as an electron bath may lead to new design principles beyond the conventional d-band theory of heterogeneous catalysis.

Zero-loss omega-filtered REM and RHEED on the new Zeiss 912

1991 ◽  
Vol 49 ◽  
pp. 616-617
Author(s):  
J.C.H. Spence ◽  
J. Mayer
Keyword(s):  
Electron Microscopy ◽  
Materials Science ◽  
Surface States ◽  
Ccd Camera ◽  
Dark Field ◽  
Ion Pump ◽  
Magnetic Imaging ◽  
Reflection Electron Microscopy ◽  
Diffraction Patterns ◽  
Large Background

The Zeiss 912 is a new fully digital, side-entry, 120 Kv TEM/STEM instrument for materials science, fitted with an omega magnetic imaging energy filter. Pumping is by turbopump and ion pump. The magnetic imaging filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient parallel (area) detection. The energy loss intensity distribution may also be displayed on the screen, and recorded by scanning it over the PMT supplied. If a CCD camera is fitted and suitable new software developed, “parallel ELS” recording results. For large fields of view, filtered images can be recorded much more efficiently than by Scanning Reflection Electron Microscopy, and the large background of inelastic scattering removed. We have therefore evaluated the 912 for REM and RHEED applications. Causes of streaking and resonance in RHEED patterns are being studied, and a more quantitative analysis of CBRED patterns may be possible. Dark field band-gap REM imaging of surface states may also be possible.

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