The Coexistence of Superconductivity and Topological Order in the Bi2Se3 Thin Films

Science ◽  
2012 ◽  
Vol 336 (6077) ◽  
pp. 52-55 ◽  
Author(s):  
Mei-Xiao Wang ◽  
Canhua Liu ◽  
Jin-Peng Xu ◽  
Fang Yang ◽  
Lin Miao ◽  
...  
Keyword(s):  
Thin Films ◽  
Three Dimensional ◽  
Surface States ◽  
Scanning Tunneling ◽  
Majorana Fermions ◽  
Topological Order ◽  
Tunneling Microscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Topological Surface ◽  
Quantum Phenomena

Three-dimensional topological insulators (TIs) are characterized by their nontrivial surface states, in which electrons have their spin locked at a right angle to their momentum under the protection of time-reversal symmetry. The topologically ordered phase in TIs does not break any symmetry. The interplay between topological order and symmetry breaking, such as that observed in superconductivity, can lead to new quantum phenomena and devices. We fabricated a superconducting TI/superconductor heterostructure by growing dibismuth triselenide (Bi2Se3) thin films on superconductor niobium diselenide substrate. Using scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we observed the superconducting gap at the Bi2Se3 surface in the regime of Bi2Se3 film thickness where topological surface states form. This observation lays the groundwork for experimentally realizing Majorana fermions in condensed matter physics.

ELECTRONIC STRUCTURE OF Ag THIN FILMS ON A Ge(001) SURFACE

2002 ◽  
Vol 09 (02) ◽  
pp. 681-686 ◽  
Author(s):  
K. NAKATSUJI ◽  
M. YAMADA ◽  
S. OHNO ◽  
Y. NAITOH ◽  
T. IIMORI ◽  
...  
Keyword(s):  
Thin Films ◽  
Electronic Structure ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Recent Observation ◽  
Three Dimensional ◽  
Surface States ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Bulk Band

We have studied the electronic structure of Ag thin films of monoatomic height grown on a Ge(001) surface at 95 K by using photoelectron spectroscopy. All the surface states on the clean Ge surface vanished and Ag 5s derived state appeared in the bulk band gap just below the Fermi level. These suggest a strong interaction with the substrate. On the other hand, on three-dimensional (3D) islands formed on a room temperature substrate, small changes were found in Ge 3d spectrum from the clean surface. Each of the Ag 3D islands already had bulklike feature in the valence band structure. The results are consistent with recent observation by scanning tunneling microscopy.

scholarly journals Scanning tunneling microscopy of superconducting topological surface states inBi2Se3

2016 ◽  
Vol 93 (22) ◽  
Author(s):  
Ian M. Dayton ◽  
Nicholas Sedlmayr ◽  
Victor Ramirez ◽  
Thomas C. Chasapis ◽  
Reza Loloee ◽  
...  
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Surface States ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Topological Surface

scholarly journals Топологические поверхностные состояния фермионов Дирака в термоэлектриках n-Bi-=SUB=-2-=/SUB=-Te-=SUB=-3-y-=/SUB=-Se-=SUB=-y-=/SUB=-

2019 ◽  
Vol 53 (5) ◽  
pp. 654
Author(s):  
Л.Н. Лукьянова ◽  
И.В. Макаренко ◽  
О.А. Усов ◽  
П.А. Дементьев
Keyword(s):  
Dirac Point ◽  
Energy Gap ◽  
Surface States ◽  
Surface Concentration ◽  
Scanning Tunneling ◽  
Fermi Velocity ◽  
Dirac Fermions ◽  
Tunneling Microscopy ◽  
Topological Surface ◽  
Local Distortions

Topological surface states of Dirac fermions in n-Bi2Te3−ySey thermoelectrics L.N. Lukyanova, I.V. Makarenko, O.A. Usov, P.A. Dementev Ioffe Institute, 194021 St. Petersburg, Russia Abstract In n-Bi2Te3 and n-Bi2Te3−ySey thermoelectrics, the surface states of Dirac fermions of the interlayer van der Waals plane (0001) were studied by scanning tunneling microscopy (STM) and spectroscopy. The surface morphology and modulated line profiles of the images in tunneling microscopy is determined by local distortions of the surface electron states density and depend on the composition. The Dirac point ED of the studied compositions is localized in the energy gap, and it shifts to the top of the valence band with increase of Se content in the solid solutions. The dependence between Dirac surface state parameters (the Dirac point position, the Fermi velocity, the fermion surface concentration) and thermoelectric properties (Seebeck coefficient and the power factor) is established for the thermoelectrics studied.

scholarly journals Room temperature strain-induced Landau levels in graphene on a wafer-scale platform

2019 ◽  
Vol 5 (11) ◽  
pp. eaaw5593 ◽  
Author(s):  
P. Nigge ◽  
A. C. Qu ◽  
É. Lantagne-Hurtubise ◽  
E. Mårsell ◽  
S. Link ◽  
...  
Keyword(s):  
Room Temperature ◽  
Landau Levels ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Model Calculations ◽  
Wafer Scale ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Quantum Phenomena ◽  
New Applications ◽  
Micrometer Scale

Graphene is a powerful playground for studying a plethora of quantum phenomena. One of the remarkable properties of graphene arises when it is strained in particular geometries and the electrons behave as if they were under the influence of a magnetic field. Previously, these strain-induced pseudomagnetic fields have been explored on the nano- and micrometer-scale using scanning probe and transport measurements. Heteroepitaxial strain, in contrast, is a wafer-scale engineering method. Here, we show that pseudomagnetic fields can be generated in graphene through wafer-scale epitaxial growth. Shallow triangular nanoprisms in the SiC substrate generate strain-induced uniform fields of 41 T, enabling the observation of strain-induced Landau levels at room temperature, as detected by angle-resolved photoemission spectroscopy, and confirmed by model calculations and scanning tunneling microscopy measurements. Our work demonstrates the feasibility of exploiting strain-induced quantum phases in two-dimensional Dirac materials on a wafer-scale platform, opening the field to new applications.

Depth Dependence of Dopant Induced Features on The Si(100)2x1:H Surface and Its Application for Three Dimensional Dopant Profiling

2001 ◽  
Vol 699 ◽  
Author(s):  
Lequn Liu ◽  
Jixin Yu ◽  
Joseph W. Lyding
Keyword(s):  
Scanning Tunneling Microscopy ◽  
Electronic Device ◽  
Three Dimensional ◽  
Surface States ◽  
Scanning Tunneling ◽  
Dopant Atom ◽  
Tunneling Microscopy ◽  
Dopant Profiling ◽  
Device Structures ◽  
Subsurface Layers

AbstractThe lack of surface states within the band gap of the perfect Si(100)2x1:H surface opens the way to scanning tunneling microscopy studies of dopant atom sites in Si(100). In this paper, Boron and Arsenic induced features are studied by ultrahigh vacuum scanning tunneling microscopy. The values of their amplitudes naturally group such that several subsurface layers can be identified. This technique for producing atom-resolved three-dimensional maps of electrically active dopants in silicon may be a useful metric for characterizing dopant profiles in ultra-small electronic device structures.

scholarly journals Native point defects and their implications for the Dirac point gap at MnBi2Te4(0001)

2022 ◽  
Vol 7 (1) ◽  
Author(s):  
M. Garnica ◽  
M. M. Otrokov ◽  
P. Casado Aguilar ◽  
I. I. Klimovskikh ◽  
D. Estyunin ◽  
...  
Keyword(s):  
Point Defects ◽  
Density Functional ◽  
Dirac Point ◽  
Density Functional Theory Calculations ◽  
Scanning Tunneling ◽  
X Ray Diffraction ◽  
Tunneling Microscopy ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Native Point Defects ◽  
Topological Surface

AbstractWe study the surface crystalline and electronic structures of the antiferromagnetic topological insulator MnBi2Te4 using scanning tunneling microscopy/spectroscopy (STM/S), micro(μ)-laser angle-resolved photoemission spectroscopy (ARPES), and density functional theory calculations. Our STM images reveal native point defects at the surface that we identify as BiTe antisites and MnBi substitutions. Bulk X-ray diffraction further evidences the presence of the Mn-Bi intermixing. Overall, our characterizations suggest that the defects concentration is nonuniform within crystals and differs from sample to sample. Consistently, the ARPES and STS experiments reveal that the Dirac point gap of the topological surface state is different for different samples and sample cleavages, respectively. Our calculations show that the antiparallel alignment of the MnBi moments with respect to those of the Mn layer can indeed cause a strong reduction of the Dirac point gap size. The present study provides important insights into a highly debated issue of the MnBi2Te4 Dirac point gap.

scholarly journals Strain-Relief Patterns and Kagome Lattice in Self-Assembled C60 Thin Films Grown on Cd(0001)

2021 ◽  
Vol 22 (13) ◽  
pp. 6880
Author(s):  
Zilong Wang ◽  
Minlong Tao ◽  
Daxiao Yang ◽  
Zuo Li ◽  
Mingxia Shi ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Kagome Lattice ◽  
Tunneling Microscopy ◽  
Kagomé Lattice ◽  
Temperature Scanning ◽  
C60 Films

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.

scholarly journals 2D weak anti-localization in thin films of the topological semimetal Pd$$_{3}$$Bi$$_{2}$$S$$_{2}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shama ◽  
R. K. Gopal ◽  
Goutam Sheet ◽  
Yogesh Singh
Keyword(s):  
Thin Films ◽  
Phonon Scattering ◽  
Surface States ◽  
Relaxation Mechanism ◽  
Transport Studies ◽  
Bulk Carriers ◽  
Topological Semimetal ◽  
Topological Surface ◽  
First Time ◽  
Electron Phonon Scattering

AbstractPd$$_{3}$$ 3 Bi$$_{2}$$ 2 S$$_{2}$$ 2 (PBS) is a recently proposed topological semimetal candidate. However, evidence for topological surface states have not yet been revealed in transport measurements due to the large mobility of bulk carriers. We report the growth and magneto-transport studies of PBS thin films where the mobility of the bulk carriers is reduced by two orders of magnitude, revealing for the first time, contributions from the 2-dimensional (2D) topological surface states in the observation of the 2D weak anti-localization (WAL) effect in magnetic field and angle dependent conductivity measurements. The magnetotransport data is analysed within the 2D Hikami-Larkin-Nagaoka (HLN) theory. The analysis suggests that multiple conduction channels contribute to the transport. It is also found that the temperature dependence of the dephasing length can’t be explained only by electron-electron scattering and that electron-phonon scattering also contributes to the phase relaxation mechanism in PBS films.

Sign in / Sign up

Export Citation Format

Share Document