scholarly journals Probing surface states of topological insulators: Kondo effect and Friedel oscillations in a magnetic field

2010 ◽  
Vol 82 (15) ◽  
Author(s):  
Minh-Tien Tran ◽  
Ki-Seok Kim
Keyword(s):  
Magnetic Field ◽  
Kondo Effect ◽  
Topological Insulators ◽  
Surface States ◽  
Friedel Oscillations

In-plane magnetic field induced helicity dependent photogalvanic effect on the surface states of topological insulators (BixSb1−x)2Te3

2021 ◽  
Vol 130 (8) ◽  
pp. 085305
Author(s):  
Shenzhong Chen ◽  
Jinling Yu ◽  
Kejing Zhu ◽  
Xiaolin Zeng ◽  
Yonghai Chen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Topological Insulators ◽  
Surface States ◽  
Photogalvanic Effect

scholarly journals Confinement Properties of the 3D Topological Insulators Bi₂Se₃, Bi₂Te₃, and Sb₂Te₃

2021 ◽  
Author(s):  
◽  
Markus Kotulla
Keyword(s):  
Magnetic Field ◽  
Topological Insulators ◽  
Surface States ◽  
Cold Atom ◽  
Zeeman Splitting ◽  
Dirac Fermion ◽  
Topological Phases ◽  
Edge States ◽  
Experimental Realization ◽  
Band Inversion

<p>Recent discoveries have spurred the theoretical prediction and experimental realization of novel materials that have topological properties arising from band inversion. Such topological insulators have conductive surface or edge states but are insulating in the bulk. How the signatures of topological behavior evolve when the system size is reduced is noteworthy from both a fundamental and an application-oriented point of view, as such understanding may form the basis for tailoring systems to be in specific topological phases. This thesis investigates the softly confined topological insulator family of Bi₂Se₃ and its properties when subjected to an in-plane magnetic field. The model system provides a useful platform for systematic study of the transition between the normal and the topological phases, including the development of band inversion and the formation of massless-Dirac-fermion surface states. The effects of bare size quantization, two-dimensional-subband mixing, and electron-hole asymmetry are disentangled and their corresponding physical consequences elucidated.  When a magnetic field is present, it is found that the Dirac cone which is formed in surface states, splits into two cones separated in momentum space and that these cones exhibit properties of Weyl fermions. The effective Zeeman splitting is much larger for the surface states than for the bulk states. Furthermore, the g-factor of the surface states depends on the size of the material. The mathematical model presented here may be realizable experimentally in the frame of optical lattices in ultra cold atom gases.</p>

scholarly journals Confinement Properties of the 3D Topological Insulators Bi₂Se₃, Bi₂Te₃, and Sb₂Te₃

2021 ◽  
Author(s):  
◽  
Markus Kotulla
Keyword(s):  
Magnetic Field ◽  
Topological Insulators ◽  
Surface States ◽  
Cold Atom ◽  
Zeeman Splitting ◽  
Dirac Fermion ◽  
Topological Phases ◽  
Edge States ◽  
Experimental Realization ◽  
Band Inversion

<p>Recent discoveries have spurred the theoretical prediction and experimental realization of novel materials that have topological properties arising from band inversion. Such topological insulators have conductive surface or edge states but are insulating in the bulk. How the signatures of topological behavior evolve when the system size is reduced is noteworthy from both a fundamental and an application-oriented point of view, as such understanding may form the basis for tailoring systems to be in specific topological phases. This thesis investigates the softly confined topological insulator family of Bi₂Se₃ and its properties when subjected to an in-plane magnetic field. The model system provides a useful platform for systematic study of the transition between the normal and the topological phases, including the development of band inversion and the formation of massless-Dirac-fermion surface states. The effects of bare size quantization, two-dimensional-subband mixing, and electron-hole asymmetry are disentangled and their corresponding physical consequences elucidated.  When a magnetic field is present, it is found that the Dirac cone which is formed in surface states, splits into two cones separated in momentum space and that these cones exhibit properties of Weyl fermions. The effective Zeeman splitting is much larger for the surface states than for the bulk states. Furthermore, the g-factor of the surface states depends on the size of the material. The mathematical model presented here may be realizable experimentally in the frame of optical lattices in ultra cold atom gases.</p>

scholarly journals Observation of spin–orbit coupling induced Weyl points in a two-electron double quantum dot

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Zoltán Scherübl ◽  
András Pályi ◽  
György Frank ◽  
István Endre Lukács ◽  
Gergő Fülöp ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Quantum Dot ◽  
Kondo Effect ◽  
Surface States ◽  
Orbit Coupling ◽  
Double Quantum ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Electronic Band ◽  
Ground State Degeneracy

Abstract Recent years have brought an explosion of activities in the research of topological aspects of condensed-matter systems. Topological phases of matter are accompanied by protected surface states or exotic degenerate excitations such as Majorana modes or Haldane’s localized spinons. Topologically protected degeneracies can, however, also appear in the bulk. An intriguing example is provided by Weyl semimetals, where topologically protected electronic band degeneracies and exotic surface states emerge even in the absence of interactions. Here we demonstrate experimentally and theoretically that Weyl degeneracies appear naturally in an interacting quantum dot system, for specific values of the external magnetic field. These magnetic Weyl points are robust against spin–orbit coupling unavoidably present in most quantum dot devices. Our transport experiments through an InAs double-dot device placed in magnetic field reveal the presence of a pair of Weyl points, exhibiting a robust ground-state degeneracy and a corresponding protected Kondo effect.

scholarly journals Discovery of a weak topological insulating state and van Hove singularity in triclinic RhBi2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kyungchan Lee ◽  
Gunnar F. Lange ◽  
Lin-Lin Wang ◽  
Brinda Kuthanazhi ◽  
Thaís V. Trevisan ◽  
...  
Keyword(s):  
Time Reversal ◽  
Topological Insulators ◽  
Dirac Point ◽  
Saddle Points ◽  
Surface States ◽  
Van Hove Singularity ◽  
Space Group ◽  
Topological Materials ◽  
Topological Surface ◽  
Optimal Space

AbstractTime reversal symmetric (TRS) invariant topological insulators (TIs) fullfil a paradigmatic role in the field of topological materials, standing at the origin of its development. Apart from TRS protected strong TIs, it was realized early on that more confounding weak topological insulators (WTI) exist. WTIs depend on translational symmetry and exhibit topological surface states only in certain directions making it significantly more difficult to match the experimental success of strong TIs. We here report on the discovery of a WTI state in RhBi2 that belongs to the optimal space group P$$\bar{1}$$ 1 ¯ , which is the only space group where symmetry indicated eigenvalues enumerate all possible invariants due to absence of additional constraining crystalline symmetries. Our ARPES, DFT calculations, and effective model reveal topological surface states with saddle points that are located in the vicinity of a Dirac point resulting in a van Hove singularity (VHS) along the (100) direction close to the Fermi energy (EF). Due to the combination of exotic features, this material offers great potential as a material platform for novel quantum effects.

scholarly journals Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Sophie Charpentier ◽  
Luca Galletti ◽  
Gunta Kunakova ◽  
Riccardo Arpaia ◽  
Yuxin Song ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Topological Insulator ◽  
Quantum Interference ◽  
Order Parameter ◽  
Thermal Strain ◽  
Surface States ◽  
Field Pattern ◽  
Key Factors ◽  
Ordered Phases ◽  
Simultaneous Existence

Abstract Topological superconductivity is central to a variety of novel phenomena involving the interplay between topologically ordered phases and broken-symmetry states. The key ingredient is an unconventional order parameter, with an orbital component containing a chiral p x  + ip y wave term. Here we present phase-sensitive measurements, based on the quantum interference in nanoscale Josephson junctions, realized by using Bi2Te3 topological insulator. We demonstrate that the induced superconductivity is unconventional and consistent with a sign-changing order parameter, such as a chiral p x  + ip y component. The magnetic field pattern of the junctions shows a dip at zero externally applied magnetic field, which is an incontrovertible signature of the simultaneous existence of 0 and π coupling within the junction, inherent to a non trivial order parameter phase. The nano-textured morphology of the Bi2Te3 flakes, and the dramatic role played by thermal strain are the surprising key factors for the display of an unconventional induced order parameter.

scholarly journals Universal scaling for the spin-electricity conversion on surface states of topological insulators

2016 ◽  
Vol 94 (2) ◽  
Author(s):  
K. T. Yamamoto ◽  
Y. Shiomi ◽  
Kouji Segawa ◽  
Yoichi Ando ◽  
E. Saitoh
Keyword(s):  
Topological Insulators ◽  
Surface States ◽  
Universal Scaling
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