scholarly journals Proximity-Induced Superconducting States of Magnetically Doped 3D Topological Insulators with High Bulk Insulation

2019 ◽  
Vol 4 (1) ◽  
pp. 9 ◽  
Author(s):  
Rikizo Yano ◽  
Hishiro Hirose ◽  
Kohei Tsumura ◽  
Shuhei Yamamoto ◽  
Masao Koyanagi ◽  
...  
Keyword(s):  
Low Temperature ◽  
Topological Insulators ◽  
Surface States ◽  
Proximity Effects ◽  
Majorana Fermions ◽  
Bulk Carrier ◽  
Metallic Conduction ◽  
Bulk Single Crystals ◽  
High Bulk ◽  
Insulating Properties

We studied magnetized topological insulator/superconductor junctions with the expectation of unconventional superconductive states holding Majorana fermions induced by superconductive proximity effects on the surface states of magnetized topological insulators (TIs), attached by conventional superconductors. We introduced Fe-doped BiSbTe2Se as an ideal magnetic TI and used the developed junction fabrication process to access the proximity-induced surface superconducting states. The bulk single crystals of the Fe-doped TI showed excellent bulk-insulating properties and ferromagnetism simultaneously at a low temperature. Meanwhile, the fabricated junctions also showed an insulating behavior above 100 K, as well as metallic conduction at a low temperature, which reflects bulk carrier freezing. In addition, we observed a proximity-induced gap structure in the conductance spectra. These results indicate that the junctions using the established materials and process are preferable to observe unconventional superconducting states which are induced via the surface channels of the magnetized TI. We believe that the developed process can be applied for the fabrication of complicated junctions and suites for braiding operations.

Topological Superconductors and Majorana Fermions

2017 ◽  
Author(s):  
Y.Y. Li ◽  
J.F. Jia
Keyword(s):  
Quantum State ◽  
Topological Insulators ◽  
Surface States ◽  
Proximity Effects ◽  
Majorana Fermions ◽  
Topological Superconductors ◽  
Atomic Chains ◽  
Recent Developments ◽  
State Of Matter ◽  
Topological Superconductivity

This article discusses recent developments relating to the so-called topological superconductors (TSCs), which have a full pairing gap in the bulk and gapless surface states consisting of Majorana fermions (MFs). It first provides a background on topological superconductivity as a novel quantum state of matter before turning to topological insulators (TIs) and superconducting heterostructures, with particular emphasis on the vortices of such materials and the Majorana mode within a vortex. It also considers proposals for realizing TSCs by proximity effects through TI/SC heterostructures as well as experimental efforts to fabricate artificial TSCs using nanowires, superconducting junctions, and ferromagnetic atomic chains on superconductors.

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 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

Detection of Surface States in Bi2 – xSbxTe3 – ySey Topological Insulators by Magnetotransport Measurements

2019 ◽  
Vol 61 (2) ◽  
pp. 99-102
Author(s):  
V. E. Sizov ◽  
V. I. Borisov ◽  
P. I. Kuznetsov ◽  
Yu. Ya. Tkach
Keyword(s):  
Topological Insulators ◽  
Surface States

scholarly journals Studies on the origin of the interfacial superconductivity of Sb2Te3/Fe1+yTe heterostructures

2019 ◽  
Vol 117 (1) ◽  
pp. 221-227 ◽  
Author(s):  
Jing Liang ◽  
Yu Jun Zhang ◽  
Xiong Yao ◽  
Hui Li ◽  
Zi-Xiang Li ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Topological Insulator ◽  
Surface States ◽  
The Other ◽  
Majorana Fermions ◽  
Bulk Conductivity ◽  
Indirect Coupling ◽  
Topological Surface ◽  
Excess Fe

The recent discovery of the interfacial superconductivity (SC) of the Bi2Te3/Fe1+yTe heterostructure has attracted extensive studies due to its potential as a novel platform for trapping and controlling Majorana fermions. Here we present studies of another topological insulator (TI)/Fe1+yTe heterostructure, Sb2Te3/Fe1+yTe, which also has an interfacial 2-dimensional SC. The results of transport measurements support that reduction of the excess Fe concentration of the Fe1+yTe layer not only increases the fluctuation of its antiferromagnetic (AFM) order but also enhances the quality of the SC of this heterostructure system. On the other hand, the interfacial SC of this heterostructure was found to have a wider-ranging TI-layer thickness dependence than that of the Bi2Te3/Fe1+yTe heterostructure, which is believed to be attributed to the much higher bulk conductivity of Sb2Te3that enhances indirect coupling between its top and bottom topological surface states (TSSs). Our results provide evidence of the interplay among the AFM order, itinerant carries from the TSSs, and the induced interfacial SC of the TI/Fe1+yTe heterostructure system.

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