surface brillouin zone
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Author(s):  
Wolfram Georg Nöhring ◽  
Jan Grießer ◽  
Patrick Dondl ◽  
Lars Pastewka

Abstract We study the surface elastic response of pure Ni, the random alloy FeNiCr and an average FeNiCr alloy in terms of the surface lattice Green's function. We propose a scheme for computing per-site Green's function and study their per-site variations. The average FeNiCr alloys accurate reproduces the mean Green's function of the full random alloy. Variation around this mean is largest near the edge of the surface Brillouin-zone and decays as $q^{-2}$ with wavevector $q$ towards the $\Gamma$-point. We also present expressions for the continuum surface Green's function of anisotropic solids of finite and infinite thickness and show that the atomistic Green's function approaches continuum near the $\Gamma$-point. Our results are a first step towards efficient contact calculations and Peierls-Nabarro type models for dislocations in high-entropy alloys.



2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yu Wang ◽  
Xiaoxi Zhou ◽  
Shanshan Li ◽  
Wenya Zhang ◽  
Chuandeng Hu ◽  
...  

AbstractNodal chain (NC) semi-metals have the degeneracy of interlacing rings in their band structure in momentum space. With the projection of degenerate rings towards crystal boundaries, there is a special type of surface dispersion appearing at surface Brillouin zone and termed drumhead surface state (DSS). Previously, experimental investigations on photonic NC and DSS have been done on metallic photonic crystals at microwave frequencies. However, far-field detection of DSS and its coupling to radiative modes in free space have not been studied. In the work, we analyze the photonic DSS in a metallic lattice by angle-resolved far-field reflection measurement and numerical simulation at terahertz (THz) frequencies, and reveal its flatness and boundness in band structure, even in the radiation continuum. Particularly, the DSS band can be tuned being from negatively dispersive via flat to positively dispersive by a single surface parameter, and the DSS at Γ point in surface Brillouin zone is in fact a symmetry-protected bound state in the continuum. Our results might have some potential applications towards THz photonics.



2020 ◽  
Vol 22 (7) ◽  
pp. 073035
Author(s):  
Andi Li ◽  
Namitha Ann James ◽  
Tianyi Wang ◽  
Zehua Wang ◽  
Hrvoje Petek ◽  
...  


2019 ◽  
Vol 116 (27) ◽  
pp. 13255-13259 ◽  
Author(s):  
Chuang-Han Hsu ◽  
Xiaoting Zhou ◽  
Tay-Rong Chang ◽  
Qiong Ma ◽  
Nuh Gedik ◽  
...  

Bismuth-based materials have been instrumental in the development of topological physics, even though bulk bismuth itself has been long thought to be topologically trivial. A recent study has, however, shown that bismuth is in fact a higher-order topological insulator featuring one-dimensional (1D) topological hinge states protected by threefold rotational and inversion symmetries. In this paper, we uncover another hidden facet of the band topology of bismuth by showing that bismuth is also a first-order topological crystalline insulator protected by a twofold rotational symmetry. As a result, its (11¯0) surface exhibits a pair of gapless Dirac surface states. Remarkably, these surface Dirac cones are “unpinned” in the sense that they are not restricted to locate at specific k points in the (11¯0) surface Brillouin zone. These unpinned 2D Dirac surface states could be probed directly via various spectroscopic techniques. Our analysis also reveals the presence of a distinct, previously uncharacterized set of 1D topological hinge states protected by the twofold rotational symmetry. Our study thus provides a comprehensive understanding of the topological band structure of bismuth.



Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2569
Author(s):  
Igor Silkin ◽  
Yury Koroteev ◽  
Vyacheslav Silkin ◽  
Evgueni Chulkov

We present a first-principles fully-relativistic study of surface and interface states in the n one monolayer (ML) Au/Pt(111) heterostructures. The modification of an unoccupied s − p -type surface state existing on a Pt(111) surface at the surface Brillouin zone center upon deposition of a few atomic Au layers is investigated. In particular, we find that the transformation process of such a surface state upon variation of the Au adlayer thickness crucially depends on the nature of the relevant quantum state in the adsorbate. When the Au adlayer consists of one or two monolayers and this relevant state has energy above the Pt(111) surface state position, the latter shifts downward upon approaching the Au adlayer. As a result, in the 1 ML Au/Pt(111) and 2 ML Au/Pt(111) heterostructures at the equilibrium adlayer position, the Pt-derived surface state experiences strong hybridization with the bulk electronic states and becomes a strong occupied resonance. In contrast, when the number n of atomic layers in the Au films increases to three or more, the Pt(111) surface state shifts upward upon reduction of the distance between the Pt(111) surface and the Au adlayer. At equilibrium, the Pt-derived surface state transforms into an unoccupied quantum-well state of the Au adlayer. This change is explained by the fact that the relevant electronic state in free-standing Au films with n ≥ 3 has lower energy in comparison to the Pt(111) surface state.



2014 ◽  
Vol 126 (2) ◽  
pp. 535-538 ◽  
Author(s):  
U. Mizutani ◽  
H. Sato ◽  
M. Inukai ◽  
E.S. Zijlstra ◽  
Q. Lin ◽  
...  


2012 ◽  
Vol 108 (22) ◽  
Author(s):  
Qian Xin ◽  
Steffen Duhm ◽  
Fabio Bussolotti ◽  
Kouki Akaike ◽  
Yoshihiro Kubozono ◽  
...  


2010 ◽  
Vol 22 (48) ◽  
pp. 485501 ◽  
Author(s):  
U Mizutani ◽  
Y Kondo ◽  
Y Nishino ◽  
M Inukai ◽  
M Feuerbacher ◽  
...  


2008 ◽  
Vol 1119 ◽  
Author(s):  
Ning Wu ◽  
Ya. B. Losovyj ◽  
Michael Manno ◽  
Chris Leighton ◽  
Peter Dowben

AbstractAngle-resolved photoemission was used to study the surface electronic band structure of ferromagnetic CoS2(below 120K) in high-quality single crystal samples. Strongly dispersing Co t2g bands are identified along the <100> k// direction. Fermi level crossings are identified along this Γ - X line (of the surface Brillouin zone) in higher resolution photoemission spectra, suggesting that the overall polarization may be controlled by the details of the band structure, particularly the surface band structure, rather than by exchange splitting on the Co atoms.



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