scholarly journals Role of topological surface states and mirror symmetry in topological crystalline insulator SnTe as an efficient electrocatalyst

Nanoscale ◽  
2021 ◽  
Author(s):  
Qing Qu ◽  
Bin Liu ◽  
Hongtao Liu ◽  
Jing Liang ◽  
Jiannong Wang ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Mirror Symmetry ◽  
Surface States ◽  
Topological Surface ◽  
Topological Crystalline Insulator

The intrinsic activities of SnTe (001) and (111) surfaces with robust topological surface states (TSSs) are superior to that of a (211) surface with fragile or without TSSs, attributing to the enhanced charge transfer between H atoms and TSSs.

scholarly journals Pure spin photocurrent in non-centrosymmetric crystals: bulk spin photovoltaic effect

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Haowei Xu ◽  
Hua Wang ◽  
Jian Zhou ◽  
Ju Li
Keyword(s):  
Mirror Symmetry ◽  
Photovoltaic Effect ◽  
Transition Metal Dichalcogenides ◽  
Spin Current ◽  
Pure Spin ◽  
Light Illumination ◽  
Metal Dichalcogenides ◽  
Critical Components ◽  
Topological Crystalline Insulator

AbstractSpin current generators are critical components for spintronics-based information processing. In this work, we theoretically and computationally investigate the bulk spin photovoltaic (BSPV) effect for creating DC spin current under light illumination. The only requirement for BSPV is inversion symmetry breaking, thus it applies to a broad range of materials and can be readily integrated with existing semiconductor technologies. The BSPV effect is a cousin of the bulk photovoltaic (BPV) effect, whereby a DC charge current is generated under light. Thanks to the different selection rules on spin and charge currents, a pure spin current can be realized if the system possesses mirror symmetry or inversion-mirror symmetry. The mechanism of BSPV and the role of the electronic relaxation time $$\tau$$ τ are also elucidated. We apply our theory to several distinct materials, including monolayer transition metal dichalcogenides, anti-ferromagnetic bilayer MnBi2Te4, and the surface of topological crystalline insulator cubic SnTe.

Influence of Electron-withdrawing Substituents on Photoelectrochemical Surface Phenomena at Phthalocyanine Thin Film Electrodes

1999 ◽  
Vol 03 (06) ◽  
pp. 444-452 ◽  
Author(s):  
TORSTEN OEKERMANN ◽  
DERCK SCHLETTWEIN ◽  
NILS I. JAEGER ◽  
DIETER WÖHRLE
Keyword(s):  
Charge Transfer ◽  
Steady State ◽  
Electrolyte Concentration ◽  
Surface States ◽  
Surface Phenomena ◽  
Time Resolved ◽  
Photogenerated Electrons ◽  
Millisecond Range ◽  
Electron Withdrawing Substituents

The influence of electron-withdrawing substituents on the photoelectrochemical properties of phthalocyanines is shown in a comparison between hexadecafluorophthalocyaninatozinc(II) ( F 16 PcZn ) and the unsubstituted phthalocyaninatozinc(II) ( PcZn ). The role of surface states in the photoelectrochemistry of both materials has been investigated by time-resolved photocurrent measurements in the millisecond range. The charging and discharging of surface states could clearly be seen as spikes at the beginning and the end of illumination. Surface states were filled with photogenerated electrons at PcZn and with photogenerated holes at F 16 PcZn . In the steady state under illumination only cathodic photocurrents were detected at PcZn , while at F 16 PcZn both cathodic and anodic photocurrents were observed. An adsorption step of electroactive species prior to the charge transfer was derived from the dependence of the steady state photocurrents on the electrolyte concentration for both materials. The concentration dependence of the charging and discharging currents, however, showed that charge transfer from surface states to the electrolyte occurs at PcZn , while at F 16 PcZn the surface states only represent recombination centres.

Many-electron theory of resonant charge transfer: Role of surface states in He andHe+scattering off Si(100)

1992 ◽  
Vol 45 (23) ◽  
pp. 13407-13416 ◽  
Author(s):  
B. L. Burrows ◽  
A. T. Amos ◽  
S. G. Davison ◽  
K. W. Sulston
Keyword(s):  
Charge Transfer ◽  
Surface States ◽  
Electron Theory ◽  
Resonant Charge Transfer

scholarly journals Ultrafast evolution of bulk, surface and surface resonance states in photoexcited $$\hbox {Bi}_{2}\hbox {Te}_{3}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hamoon Hedayat ◽  
Davide Bugini ◽  
Hemian Yi ◽  
Chaoyu Chen ◽  
Xingjiang Zhou ◽  
...  
Keyword(s):  
Surface States ◽  
Photoemission Spectroscopy ◽  
Time Resolved ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Interband Scattering ◽  
Surface Resonance ◽  
Bulk Surface ◽  
Unpolarized Electron ◽  
Topological Surface

AbstractWe use circular dichroism (CD) in time- and angle-resolved photoemission spectroscopy (trARPES) to measure the femtosecond charge dynamics in the topological insulator (TI) $$\hbox {Bi}_{2}\hbox {Te}_{3}$$ Bi 2 Te 3 . We detect clear CD signatures from topological surface states (TSS) and surface resonance (SR) states. In time-resolved measurements, independently from the pump polarization or intensity, the CD shows a dynamics which provides access to the unexplored electronic evolution in unoccupied states of $$\hbox {Bi}_{2}\hbox {Te}_{3}$$ Bi 2 Te 3 . In particular, we are able to disentangle the unpolarized electron dynamics in the bulk states from the spin-textured TSS and SR states on the femtosecond timescale. Our study demonstrates that photoexcitation mainly involves the bulk states and is followed by sub-picosecond transport to the surface. This provides essential details on intra- and interband scattering in the relaxation process of TSS and SR states. Our results reveal the significant role of SRs in the subtle ultrafast interaction between bulk and surface states of TIs.

scholarly journals Phase diagrams of superconducting topological surface states

2021 ◽  
Vol 24 (4) ◽  
pp. 43701
Author(s):  
W. Zhao ◽  
L. Ding ◽  
B. Zhou ◽  
J. Wu ◽  
Y. Bai ◽  
...  
Keyword(s):  
Phase Diagrams ◽  
Time Reversal ◽  
Mirror Symmetry ◽  
Surface States ◽  
Time Reversal Symmetry ◽  
And Topology ◽  
Topological Surface ◽  
Iron Based ◽  
Crystalline Symmetry

In this paper, we present a detailed study on the phase diagrams of superconducting topological surface states, especially, focusing on the interplay between crystalline symmetry and topology of the effective BdG Hamiltonian. We show that for the 4 x 4 kinematic Hamiltonian of the normal state, a mirror symmetry M can be defined, and for the M-odd pairings, the classification of the 8 x 8 BdG Hamiltonian is ℤ⊕ℤ, and the time-reversal symmetry is broken intrinsically. The topological non-trivial phase can support chiral Majorana edge modes, and can be realized in the thin films of iron-based superconductor such as FeSeTe.

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.

scholarly journals JOSEPHSON CURRENT TRANSFER BY WEYL TOPOLOGICAL SEMIMETALS SURFACE STATES

2020 ◽  
Author(s):  
Eduard Devyatov ◽  
Keyword(s):  
Charge Transfer ◽  
Josephson Effect ◽  
Surface States ◽  
Josephson Current ◽  
Hybrid Structures ◽  
Current Transfer ◽  
Weyl Semimetals ◽  
Topological Surface ◽  
Topological Semimetals

Experiments on the study of topological surface states of magnetic and nonmagnetic Weyl semimetals charge transfer are presented. For surface states contribution the stationary and nonstationary Josephson effect realized at superconductortopological semi-metal-superconductor hybrid structures is applied.

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