scholarly journals Spin-orbit Coupled Surface States Revealed with Spin- and Angle-resolved Photoemission Spectroscopy Using a Polarization-variable Light

2021 ◽  
Vol 64 (6) ◽  
pp. 275-280
Author(s):  
Koichiro YAJI
Keyword(s):  
Surface States ◽  
Photoemission Spectroscopy ◽  
Spin Orbit ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Variable Light

Thermopower Measurements of Arrays of Small Diameter (18-60 nm) Bi Nanowires

2007 ◽  
Vol 1044 ◽  
Author(s):  
Tito Huber ◽  
A. Adeyeye ◽  
T. Odunfa ◽  
A. Nikolaeva ◽  
L. Konopko ◽  
...  
Keyword(s):  
Small Diameter ◽  
Surface States ◽  
Theoretical Work ◽  
Heavy Ion ◽  
Nanowire Arrays ◽  
Photoemission Spectroscopy ◽  
Spin Orbit ◽  
Angle Resolved Photoemission Spectroscopy ◽  
High Carrier ◽  
Very High

AbstractTheoretical work based on one-dimensional (1D) models indicates that Bi wires with diameter smaller than 50 nm can exhibit superior thermoelectric properties since the density of states at the Fermi level of a 1D system can be tuned to very high values. Recently, angle-resolved photoemission spectroscopy (ARPES) studies of Bi surfaces have shown that Bi nanowires support Rashba spin-orbit surface states, with high carrier densities of around 5×1012/cm−2, that have not been considered in current models of Bi nanowires. According to our estimates, the sheath of surface charge on Bi nanowires should contribute substantially to the thermopower of Bi nanowires. We carried out an experimental study of the transport properties and thermopower of bismuth nanowire arrays (NWA) with wire diameters ranging between 60 nm and 13 nm to investigate these phenomena. The Rashba interaction is a spin orbit interaction that is important for surfaces of materials consisting of heavy ion elements; thermoelectric materials frequently consist of these elements (i.e.PbTe) because they scatter phonons and form low thermal conductivity materials.

Sodium Doping of Bi/Si(111) Ultra-Thin Films

2014 ◽  
Vol 213 ◽  
pp. 65-70
Author(s):  
Maria V. Ryzhkova ◽  
Dimitry V. Gruznev ◽  
Elena A. Borisenko ◽  
Dmitry A. Tsukanov
Keyword(s):  
Thin Films ◽  
Electrical Conductance ◽  
Surface States ◽  
Surface Conductivity ◽  
Metallic Surface ◽  
Photoemission Spectroscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Sodium Doping ◽  
Reconstructed Surfaces ◽  
Conductance Changes

Changes in electrical conductance of the Bi/Si (111) reconstructed surfaces and Bi {012} or Bi (001) ultra-thin films have been studied after sodium deposition at room temperature. It was observed that deposition of sodium onto Si (111)-β-3×3-Bi surface results in increasing of surface conductivity up to 0.3 monolayers (ML) of adsorbed sodium atoms. These conductance changes were explained by developing of the metallic surface states in the band gap as revealed by angle resolved photoemission spectroscopy spectra. Moreover, it was shown that sodium adsorption onto Bi {012} and Bi (001) thin films leads to drastic changes in its surface conductivity including a peak of maximum electrical conductance at 0.5 monolayers of adsorbed sodium.

scholarly journals Photoemission Spectroscopic Evidence of Multiple Dirac Cones in Superconducting BaSn3

2021 ◽  
Vol 38 (10) ◽  
pp. 107403
Author(s):  
Zhe Huang ◽  
Xianbiao Shi ◽  
Gaoning Zhang ◽  
Zhengtai Liu ◽  
Soohyun Cho ◽  
...  
Keyword(s):  
Surface States ◽  
Photoemission Spectroscopy ◽  
Rotational Axis ◽  
Type I ◽  
Dirac Fermions ◽  
First Principles Calculations ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Topological Quantum ◽  
Topological Surface ◽  
Single Material

Signatures of topological superconductivity (TSC) in superconducting materials with topological nontrivial states prompt intensive researches recently. Utilizing high-resolution angle-resolved photoemission spectroscopy and first-principles calculations, we demonstrate multiple Dirac fermions and surface states in superconductor BaSn3 with a critical transition temperature of about 4.4 K. We predict and then unveil the existence of two pairs of type-I topological Dirac fermions residing on the rotational axis. Type-II Dirac fermions protected by screw axis are confirmed in the same compound. Further calculation for the spin helical texture of the observed surface states originating from the Dirac fermions gives an opportunity for realization of TSC in one single material. Hosting multiple Dirac fermions and topological surface states, the intrinsic superconductor BaSn3 is expected to be a new platform for further investigation of topological quantum materials as well as TSC.

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.

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