### ?

## SURFACE STATES IN A 3D TOPOLOGICAL INSULATOR: THE ROLE OF HEXAGONAL WARPING AND CURVATURE

JETP Letters. 2015. Vol. 148. No. 3. P. 509.

Burmistrov I., Repin E.

In press

We explore a combined effect of hexagonal warping and a finite effective mass on both the tunneling density of electronic surface states and the structure of Landau levels of 3D topological insulators. We find the increasing warping to transform the square-root van Hove singularity into a logarithmic one. For moderate warping, an additional logarithmic singularity and a jump in the tunneling density of surface states appear. By combining the perturbation theory and the WKB approximation, we calculate the Landau levels in the presence of hexagonal warping. We predict that due to the degeneracy removal, the evolution of Landau levels in the magnetic field is drastically modified.

Frolov A. V., Orlov A. P., Sinchenko A. A. et al., Journal of Physics: Conference Series 2018 Vol. 941 P. 1–4

We report preparation of nanoribbons (crossection ~ 250*25 nm2) by focused ion beam etching of single-crystalline Bi2Se3 and detailed measurements of their magnetoresistance at temperatures down to 4.2 K, magnetic field up to 9 T. In a magnetic field parallel to the axis of nanowire the magnetoresistance shows up oscillations. Surprisingly, the Fourier analysis shows ...

Added: February 25, 2018

Aronzon B. A., Oveshnikov L. N., Prudkoglyad V.A. et al., Journal of Magnetism and Magnetic Materials 2018 Vol. 459 No. 1 P. 331–334

Structural, magnetic and magnetotransport properties of (Bi1-xEux)2Se3 thin films have been studied experimentally as a function of Eu content. The films were synthesized by MBE. It is demonstrated that Eu distribution is not uniform, it enter quint-layers forming inside them plain (pancake-like) areas containing Eu atoms, which sizes and concentration increase with the growth of Eu content. Positive ...

Added: July 13, 2018

S. V. Demishev, Gilmanov M. I., Samarin A. N. et al., Applied Magnetic Resonance 2020 Vol. 51 No. 1 P. 71–84

The low temperature (T < 5 K) electron spin resonance in topological Kondo insulator SmB6 is investigated. It is shown that spin relaxation time of the paramagnetic centers responsible for low temperature electron spin resonance in SmB6 is about ~ 10−8 s, which exceeds by five orders of magnitude the widely accepted spin and charge fluctuation time ~ 10−13 s in the homogeneous ...

Added: December 24, 2020

Мальшуков А. Г., Physical Review B: Condensed Matter and Materials Physics 2019 Vol. 100 P. 035301-1–035301-7

A nonstationary anomalous Hall current is calculated for a voltage biased Josephson junction, which is composed of two s-wave superconducting contacts deposited on the top of a three-dimensional topological insulator (TI). A homogeneous Zeeman field was assumed at the surface of the TI. The problem has been considered within the ballistic approximation and on the ...

Added: March 11, 2020

Овешников Л. Н., Нехаева Е. И., Прудкогляд В. А. et al., Письма в Журнал экспериментальной и теоретической физики 2016 Т. 104 № 9 С. 651–657

В работе исследовалась магнетопроводимость тонких пленок Bi2Se3 с защитным слоем Se, выра
щенных на подложках (111) BaF2. Наблюдаемая отрицательная магнетопроводимость в малых полях,
обусловленная эффектом слабой антилокализации, так же как и осцилляции Шубникова–де Гааза в
больших полях, определяется только перпендикулярной к плоскости пленки компонентой магнитного
поля. Полученные экспериментальные результаты могут быть разумно объяснены в предположении на
личия в исследуемых пленках ...

Added: December 6, 2016

Kukushkin I., Vankov A., Kaysin B., Physical Review B: Condensed Matter and Materials Physics 2017 Vol. 96 P. 235401-1–235401-8

We perform a magneto-optical study of a two-dimensional electron systems in the regime of the Stoner
ferromagnetic instability for even quantum Hall filling factors on MgxZn1−xO/ZnO heterostructures. Under
conditions of Landau-level crossing, caused by enhanced spin susceptibility in combination with the tilting of the
magnetic field, the transition between two rivaling phases, paramagnetic and ferromagnetic, is traced in ...

Added: December 19, 2017

Бисноватый-Коган Г. С., Kondratyev I., Успехи физических наук 2021 Т. 191 № 5 С. 543–557

The thermodynamic properties of electron gas under the extreme conditions of high temperature, high matter density, and/or a strong magnetic field largely determine the behavior of matter in upper layers of neutron stars and accretion columns of magnetized neutron stars in binary systems. A strong magnetic field in these objects makes the motion of electrons ...

Added: March 29, 2022

Alexander P. Protogenov, Verbus V. A., Chulkov E., Physical Review B: Condensed Matter and Materials Physics 2013 Vol. 88 No. 19 P. 195431-1–195431-4

We use the N-terminal scheme for studying the edge-state transport in two-dimensional topological insulators. We find the universal nonlocal response in the ballistic transport approach. This macroscopic exhibition of the topological order offers different areas for applications. ...

Added: December 25, 2013

Alexey A. Sokolik, Yurii E. Lozovik, Physical Review B: Condensed Matter and Materials Physics 2019 Vol. 99 No. 08-5423 P. 085423-1–085423-12

We present the theory of many-body corrections to cyclotron transition energies in graphene in strong magnetic field due to Coulomb interaction, considered in terms of the renormalized Fermi velocity. A particular emphasis is made on the recent experiments where detailed dependencies of this velocity on the Landau level filling factor for individual transitions were measured. ...

Added: March 8, 2019

Mal'shukov A., Physical Review B: Condensed Matter and Materials Physics 2020 Vol. 101 P. 134514-1–134514-7

A nonuniform in-plane Zeeman field can induce spontaneous supercurrents of spin-orbit-coupled electrons in
superconducting two-dimensional systems and thin films. In this work it is shown that current vortices can be
created at the ends of a long homogeneously magnetized strip of a ferromagnetic insulator, which is deposited on
the surface of a three-dimensional topological insulator. The s-wave superconductivity ...

Added: January 20, 2021

A. A. Sokolik, Zabolotskiy A. D., Yu. E. Lozovik, Physical Review B: Condensed Matter and Materials Physics 2017 Vol. 95 No. 12-5402 P. 125402-1–125402-7

In strong magnetic fields, massless electrons in graphene populate relativistic Landau levels with the square-root dependence of each level energy on its number and magnetic field. Interaction-induced deviations from this single-particle picture were observed in recent experiments on cyclotron resonance and magneto-Raman scattering. Previous attempts to calculate such deviations theoretically using the unscreened Coulomb interaction ...

Added: March 1, 2017

Sisakht E. T., Fazileh F., Hashemifar S. J. et al., Physical Review B: Condensed Matter and Materials Physics 2023 Vol. 107 No. 12 Article 125417

Two-dimensional gapped semi-Dirac (GSD) materials are systems with a finite band gap that whose carriers behave relativistically in one direction and Schrödinger-like in the other. In the present paper, we show that besides the two well-known energy band features (curvature and chirality), the band-gap parameter also plays a crucial role in the index and magnetic-field ...

Added: November 2, 2023

Kuntsevich A., Materials 2022 Vol. 14 No. 24 P. 7528–7528

Search for doped superconducting topological insulators is of prime importance for new quantum technologies. We report on fabrication of Sr-doped Bi2Te3 single crystals. We found that Bridgman grown samples have p-type conductivity in the low 10^19 cm^(−3), high mobility of 4000 cm^2*V^(−1)s^(−1), crystal structure independent on nominal dopant content, and no signs of superconductivity. We also studied molecular ...

Added: June 17, 2022

Vasenko A. S., Golubov A. A., Silkin V. M. et al., JETP Letters 2017 Vol. 105 No. 8 P. 489–490

We study the effect of the Fermi surface anisotropy (hexagonal warping) on the superconducting pair potential, induced in a three-dimensional topological insulator (TI) by proximity with an s-wave superconductor (S) in presence of a magnetic moment of a nearby ferromagnetic insulator (FI). In the previous studies similar problem was treated with a simplified Hamiltonian, describing ...

Added: April 7, 2017

A.G. Mal'shukov, Physical Review B: Condensed Matter and Materials Physics 2018 Vol. 97 P. 064515-1–064515-7

It is shown that the spin-orbit and Zeeman interactions result in phase shifts of Andreev-reflected
holes propagating at the surface of a topological insulator, or in Rashba spin-orbit-coupled two
dimensional normal metals, which are in a contact with an s-wave superconductor. Due to interference
of holes reflected through different paths of Andreev interferometer the electric current through
external contacts ...

Added: February 6, 2019

Verbus V. A., Protogenov A. P., Chulkov E., / Cornell University. Series cond-mat "arxiv.org". 2014. No. 1406.1507.

Weyl semimetal is a three-dimensional material with a conical spectrum near an even number of point nodes, where two bands touch each other. Here we study spectral properties of surface electron states in such a system. We show that the density of surface states possesses a logarithmic singularity for the energy to 0. It decreases ...

Added: March 8, 2016

Backens S., Shnirman A., Makhlin Y., JETP Letters 2022 Vol. 116 No. 12 P. 891–895

We consider Majorana zero modes in a Josephson junction on top of a topological insulator in transverse magnetic field. Majorana zero modes reside at periodically located nodes of Josephson vortices. We find that hybridization of these modes is prohibited by symmetries of the problem at vanishing chemical potential, which ensures better protection of zero modes ...

Added: December 10, 2022

Pudalov V., Сахин В. О., Куковицкий Е. Ф. et al., Письма в Журнал экспериментальной и теоретической физики 2022 Т. 115 № 4 С. 270–276

The formation of nanosized charge droplets in the bulk of a three-dimensional topological insulator
Bi1.08Sn0.02Sb0.9Te2S was evidenced using electron spin resonance. Since electrons and holes are “locked” in
these droplets far apart from each other, their participation in bulk conductivity is possible only due to thermal
activation or to variable range hopping. Our transport measurements give evidence that ...

Added: November 16, 2022

T. Karabassov, A.A. Golubov, Silkin V. M. et al., Physical Review B: Condensed Matter and Materials Physics 2021 Vol. 103 P. 224508-1–224508-9

Superconducting hybrid structures with topological order and induced magnetization offer a promising way to realize fault-tolerant quantum computation. However, the effect of the interplay between magnetization and the property of the topological insulator surface, otherwise known as spin-momentum locking on the superconducting proximity effect, still remains to be investigated. We relied on the quasiclassical self-consistent ...

Added: June 4, 2021

Kuntsevich A., Shupletsov A. V., Minkov G. M., Physical Review B: Condensed Matter and Materials Physics 2018 Vol. 97 P. 195431-1–195431-8

The phase of quantum magneto-oscillations is often associated with the Berry phase and is widely used to
argue in favor of topological nontriviality of the system (Berry phase 2πn + π). Nevertheless, the experimentally
determined value may deviate from 2πn + π arbitrarily, therefore more care should be made analyzing the
phase of magneto-oscillations to distinguish trivial systems ...

Added: September 10, 2018

Karabassov T., Vasenko A., Известия Уфимского научного центра РАН 2021 Т. 1 С. 10–16

Materials that possess strong spin-orbit interaction have provoked great interest over the past few years, in
particular, in the actively developing field of quantum calculations. A topological insulator is a good example of
such a material. The topological insulator has high surface conductivity, whereas in the body it shows the properties
of an insulator, this being a purely ...

Added: December 30, 2020

Alexey A. Sokolik, Yurii E. Lozovik, Physical Review B: Condensed Matter and Materials Physics 2024 Vol. 109 No. 16 Article 165430

Edge magnetoplasmons arise on a boundary of conducting layers in perpendicular magnetic field due to an interplay of electron cyclotron motion and Coulomb repulsion. Lateral electric field, which confines electrons inside the sample, drives their spiraling motion in magnetic field along the edge with the average drift velocity contributing to the total magnetoplasmon velocity. We ...

Added: April 23, 2024

Alexey A. Sokolik, Yurii E. Lozovik, Physical Review B: Condensed Matter and Materials Physics 2019 Vol. 100 No. 12 P. 125409-1–125409-8

Magnetoplasmons on graphene edges in quantizing magnetic fields are investigated at different Landau-level filling factors. To find the mode frequency, the optical conductivity tensor of disordered graphene in a magnetic field is calculated in the self-consistent Born approximation, and the nonlocal electromagnetic problem is solved using the Wiener-Hopf method. Magnetoplasmon dispersion relations, velocities, and attenuation ...

Added: October 18, 2019

Alexey A. Sokolik, Yurii E. Lozovik, Physical Review B: Condensed Matter and Materials Physics 2018 Vol. 97 No. 07-5416 P. 1–8

Renormalization of Landau level energies in graphene in strong magnetic field due to Coulomb interaction is studied theoretically, and calculations are compared with two experiments on carrier-density dependent scanning tunneling spectroscopy. An approximate preservation of the square-root dependence of the energies of Landau levels on their numbers and magnetic field in the presence of the ...

Added: November 28, 2017