Yu. M. Koroteev

• Russian Academy of Sciences

Nowadays, the application of protective multicomponent coatings based on hard metal nitrides is increasingly used to increase the resistance of structures and tools to wear, corrosion and oxidation. In the present work, the multicomponent system Ti-Al-Ta-Si-N is studied, which has high hardness and crack resistance combined with thermal stability a...

Nowadays, the application of multicomponent coatings with multiphase nanocrystalline structure is the most promising direction in the search for wear-resistant protective coatings with a full set of necessary operational properties. Nanocrystalline multicomponent coatings based on the Ti-Al-Ta-Si-N system have a high hardness combined with thermal...

In this work, we study, in the framework of the ab initio linear-response time-dependent density functional theory, the low-energy collective electronic excitations with characteristic sound-like dispersion, called acoustic plasmons, in bulk ferromagnetic nickel. Since the respective spatial oscillations in slow and fast charge systems involve stat...

New temperature scales and remarkable differences from bulk properties have increasingly placed the surfaces of strongly correlated f materials into the focus of research activities. Applying first‐principles calculations and angle‐resolved photoelectron spectroscopy measurements, a strong Rashba effect and spin‐split surface states at the CeIn sur...

Using density functional theory, we propose the (MnSb2Te4)·(Sb2Te3) n family of stoichiometric van der Waals compounds that harbor multiple topologically nontrivial magnetic phases. In the ground state, the first three members of the family (n = 0, 1, 2) are 3D antiferromagnetic topological insulators, while for n ≥ 3 a special phase is formed, in...

Combining robust magnetism, strong spin-orbit coupling and unique thickness-dependent properties of van der Waals crystals could enable new spintronics applications. Here, using density functional theory, we propose the (MnSb$_2$Te$_4$)$\cdot$(Sb$_2$Te$_3$)$_n$ family of stoichiometric van der Waals compounds that harbour multiple topologically-non...

The effect of spin-orbit coupling on quantum well states (QWSs) in atomically thin Ir adlayers deposited on the Au(111) substrate is studied in the framework of the density functional theory. Varying the Ir film thickness from 1 to 3 atomic layers, we find numerous Ir-derived QWSs, which are mainly of d character. The resulting band dispersion of Q...

Magnetic topological insulators are narrow-gap semiconductor materials that combine non-trivial band topology and magnetic order¹. Unlike their nonmagnetic counterparts, magnetic topological insulators may have some of the surfaces gapped, which enables a number of exotic phenomena that have potential applications in spintronics¹, such as the quant...

We present a first-principles study of the GdRh2Si2(001) surface electronic structure. Two surfaces, Si- and Gd-terminated, are considered. The origin of the two-dimensional (2D) electronic states at both terminations is investigated by tracing the band structure evolution by going from individual Si, Rh, and Gd atomic layers to (non)stoichiometric...

Application of the Luttinger theorem to the Kondo lattice YbRh2Si2 suggests that its large 4f-derived Fermi surface (FS) in the paramagnetic (PM) regime should be similar in shape and volume to that of the divalent local-moment antiferromagnet (AFM) EuRh2Si2 in its PM regime. Here we show by angle-resolved photoemission spectroscopy that paramagnet...

The paper presents a first-principle calculation of the influence of lattice defects (a hydrogen atom, a vacancy and a helium-in-vacancy complex) and their concentration on the core electron binding energies in zirconium atoms. It is shown that the formation of a vacancy or a helium-in-vacancy complex causes core-level shifts of Zr atoms to lower b...

We present the density functional calculation results for K adsorption on Pt(111) in a (√3 × √3)R30° structure. The site preference, surface relaxation, work function, and electron structure of the system are analyzed. The hcp hollow position is found to be the most favorable for K adsorption. The calculated surface relaxations and adsorption geome...

We presents a first-principles investigation on the interaction energy of hydrogen and vacancies with α-zirconium. It is established that the presence of vacancies in zirconium increases the hydrogen–metal binding energy; the presence of hydrogen in the zirconium lattice reduces the vacancy formation energy. It is shown that hydrogen and vacancies...

We report an ab initio study of the effect of pressure on vibrational and electronic properties of K3Bi and Rb3Bi in the cubic Fm3¯m structure. It is shown that the high-temperature cubic phase of K3Bi and Rb3Bi is dynamically unstable at T=0 but can be stabilized by pressure. The electronic spectra of alkali bismuthides are found to possess the bu...

An interplay of spin–orbit coupling and intrinsic magnetism is known to give rise to the quantum anomalous Hall and topological magnetoelectric effects under certain conditions. Their realization could open access to low power consumption electronics as well as many fundamental phenomena like image magnetic monopoles, Majorana fermions and others....

The electronic structure and topological properties of the AIIMg2Bi2 (AII = Mg,Ca,Sr,Ba) compounds are theoretically studied with the use of exact exchange. It is found that the Mg3Bi2 compound in the equilibrium state is a semimetal, whereas three other compounds are semiconductors with a direct fundamental band gap. It is predicted that the uniax...

The ab initio investigations have been performed for the atomic structure of the Zr–He, Zr–vac, and Zr–vac–He systems with concentrations of helium atoms and vacancies (vac) of ~6 at %. A heliuminduced instability of the zirconia lattice has been revealed in the Zr–He system, which disappears with the formation of vacancies. The most preferred posi...

Spin-polarized two-dimensional electron states (2DESs) at surfaces and interfaces of magnetically active materials attract immense interest because of the idea of exploiting fermion spins rather than charge in next generation electronics. Applying angle-resolved photoelectron spectroscopy, we show that the silicon surface of GdRh2Si2 bears two dist...

Strong topological insulators (TIs) support topological surfaces states on any crystal surface. In contrast, a weak, time-reversal-symmetry-driven TI with at least one non-zero v1, v2, v3 ℤ2 index should host spin-locked topological surface states on the surfaces that are not parallel to the crystal plane with Miller indices (v1 v2 v3). On the othe...

Ab initio calculations of the electronic structures of the Zr-He, Zr-H, and Zr-He-H systems have been carried out. The effect of impurities of hydrogen and helium on the electronic structure of hpc Zr has been considered. It has been found that the 1s states form a narrow band below the conduction band bottom of Zr. Unlike helium, hydrogen dissolvi...

We report the bulk and surface electronic properties and spin polarization of a rich family of Sn-based ternary topological insulators studied by means of first-principles calculations within the framework of density functional theory. These compounds exist with the following stoichiometries: SnX2Te4,SnX4Te7, and SnBi6Te10 (X = Sb and Bi). Where a...

This chapter focuses on different two-dimensional (2D) topological insulators (TIs), and introduces the basic concepts through the example of graphene and discusses the HgTe/CdTe quantum wells. It shows that the actual material parameters that allow assessing the usefulness of a selected system for experimental purposes can only be obtained from ab...

Ab initio calculations of electronic structures of Zr–H and Zr–He systems have been done. The influence of hydrogen or helium impurities on the electron density distribution of the host metal has been considered. Extremely inhomogeneous redistribution of the metal valence charge density within the first coordination sphere of the impurity was found...

The results of ab initio calculations of diffusion barriers for a hydrogen atom in zirconium α phase have been presented. The potential barrier and length of the jumps have been obtained for all possible directions of hydrogen diffusion. Also the influence of local lattice distortion caused by the presence of impurity on the height and shape of the...

Ab initio calculations of the electronic structure of hexagonal close-packed and face-centered cubic zirconium with the impurity of helium atoms of about 6 at % have been performed. It has been established that the presence of helium significantly changes the electronic structure of zirconium and leads to a considerable redistribution of its electr...

We present ab initio density functional theory (DFT) calculation results for electronic and spin structures of both the Te- and Sn-terminated SnTe(111) polar surfaces. Rocksalt narrow-gap semiconductor SnTe belongs to the recently discovered class of topological crystalline insulators in which the topological nature of surface electronic states ari...

Carrying a large, pure spin magnetic moment of 7 μB per atom in the half-filled 4f shell, divalent europium is an outstanding element for assembling novel magnetic devices in which a two-dimensional electron gas may be polarized due to exchange interaction with an underlying magnetically-active Eu layer. Here we show that the Si-Rh-Si surface trila...

We present ab initio calculations of an electronic structure and a topological invariant ν0 of the Ge2Sb2Te5 compound. We have found that in the case of equiatomic composition of Ge/Sb layers the Ge2Sb2Te5 compound is the topological insulator. The ν0 invariant does not depend on a specific location of Ge and Sb atoms in the mixed layers, and depen...

The electronic structure of quaternary natural minerals PbBi2Te2S2 (aleksite), Pb2Bi2Te2S3 (saddlebackite), and PbBi4Te4S3 (C phase) has been theoretically studied. These compounds have a layered structure: aleksite and saddlebackite are formed by seven- and nine-layer blocks, respectively, and C phase consists of five- and seven-layer blocks separ...

The unoccupied part of the band structure of topological insulators Bi$_2$Te$_{x}$Se$_{3-x}$ ($x=0,2,3$) is studied by angle-resolved two-photon photoemission and density functional theory. For all surfaces linearly-dispersing surface states are found at the center of the surface Brillouin zone at energies around 1.3 eV above the Fermi level. Theor...

The first experimental evidence is presented of the topological insulator state in PbBi$_{2}$Te$_{4}$. A single surface Dirac cone is observed by angle-resolved photoemission spectroscopy (ARPES) with synchrotron radiation. Topological invariants $\mathbb{Z}_2$ are calculated from the {\it ab initio} band structure to be 1; (111). The observed two-...

The experimental evidence is presented of the topological insulator state in PbBi2Te4. A single surface Dirac cone is observed by angle-resolved photoemission spectroscopy with synchrotron radiation. Topological invariants Z2 are calculated from the ab initio band structure to be 1;(111). The observed two-dimensional isoenergy contours in the bulk...

The experimental evidence is presented of the topological insulator state in PbBi 2 Te 4. A single surface Dirac cone is observed by angle-resolved photoemission spectroscopy with synchrotron radiation. Topological invariants Z 2 are calculated from the ab initio band structure to be 1;(111). The observed two-dimensional isoenergy contours in the b...

The electronic structure of ternary compounds Pb2Sb2Te5, Pb2Bi2Te5, and Pb2Bi2Se5, which have a layered structure that consists of nine-layer atomic blocks separated by van der Waals gaps, has been theoretically studied. It has been shown that all studied compounds are three-dimensional topological insulators. The possibility of the existence of a...

The supercell Pd16H has been investigated in order to describe the hydrogen migration in the palladium lattice, where the hydrogen atom moves between symmetric interstitial sites. Ab initio calculations of the barriers for hydrogen diffusion in relaxed and unrelaxed metal lattices have been performed in the local density approximation, and the char...

We analyze the crystal and electronic structures of Tl-based strong topological insulators TlSbTe2, TlSbSe2, TlBiTe2, and TlBiSe2 by using first-principles calculation results. The topological nature of these materials is characterized by a single Dirac cone at the Γ̄ point. Aside from the latter robust surface state (SS), we find trivial SSs at (a...

The electronic structure of AIVBVI · A2VB3VI ternary compounds consisting of seven-layer atomic blocks separated by van der Waals gaps has been theoretically investigated. The YbBi(Sb)2Te4 compounds have been considered, for which a similar atomic structure has been predicted. It has been shown that most compounds based on Group IV elements, as wel...

Theoretical studies of the bulk and surface electronic structures of PbBi4Te7 are presented. The PbBi4Te7 compound has a layered structure of five-layer (Bi2Te3) and seven-layer (PbBi2Te4) blocks alternating along the hexagonal axis. Analysis of the spin-orbit-induced inversion of the band gap edges indicates that this compound is a three-dimension...

The results of the theoretical investigation of the bulk and surface electronic structures of Tl-V-VI2 compounds, where V is the Bi or Sb semimetal and VI is the Se or Te chalcogen, are reported. It has been shown that these compounds are three-dimensional topological insulators. Both a topologically protected surface state, which forms a Dirac con...

We present a combined experimental and theoretical study of the surface structure of single crystal Bi(100) via scanning tunneling microscopy (STM), low-energy electron diffraction intensity versus energy (LEED-IV) analysis and density functional theory (DFT). We find that the surface is unreconstructed and shows an unusually large oscillatory mult...

Employing first-principles calculations, we studied the electronic structure of ultrathin Bi–Sb films, focusing on the appearance of surface or edge states that are topologically protected. Our calculations show that in ordered structures the Bi–Sb bonds are quite strong, forming well-defined double layers that contain both elements. We find surfac...

The results of the theoretical investigation of the surface electronic structure of A2VB3VI compounds containing topologically protected surface states are reported. The ideal Bi2Te3, Bi2Se3, and Sb2Te3 surfaces and surfaces with an absent external layer of chalcogen atoms, which were observed experimentally as monolayer terraces, have been conside...

We report on the observation of a giant spin-orbit splitting of quantum-well states in the unoccupied electronic structure of a Bi monolayer on Cu(111). Up to now, Rashba-type splittings of this size have been reported exclusively for surface states in a partial bandgap. With these quantum-well states we have experimentally identified a second -- a...

We report on the observation of a giant spin-orbit splitting of quantum-well states in the unoccupied electronic structure of a Bi monolayer on Cu(111). Up to now, Rashba-type splittings of this size have been reported exclusively for surface states in a partial band gap. With these quantum-well states we have experimentally identified a second cla...

A theoretical study of collective electronic excitations in Pd at low-energy (from 0 to ∼3 eV) domain is reported. The calculations were performed with full inclusion of the electron band structure obtained within self-consistent pseudopotential approach. We show that the presence in Pd of two kinds of carriers (in s‐p and d bands) at the Fermi lev...

Ab initio studies are carried out for the atomic and electronic structures of the Zr-He system. It is revealed that zirconium undergoes a phase transition induced by helium. The most preferred position of the impurity in the metal lattice is determined. The energy of dissolution of helium and the excess volume introduced by helium are calculated. I...

We report on ballistic electron emission microscopy and spectroscopy studies on epitaxial (3-5 nm thick) Bi(111) films, grown on n-type Si substrates. The effective barrier heights of the Schottky barrier observed are 0.58 eV for the Bi/Si(100)-(2x1) and 0.68 eV for the Bi/Si(111)-(7x7). At the step edges of the epitaxial films a strong increase of...

It is important that the hydrogen yield occurs from the entire sample surface even when only a small fraction of the sample was irradiated [4]. The results obtained completely exclude the possibility of using the thermal mechanism to explain the observed effect. In the present study, we make an attempt to substantiate the plasmon mechanism as that...

Due to their electronic similarity with graphene sheets, surfaces and thin films of the semimetal bismuth have recently received considerable interest. A systematic study of thin (1-6 bilayers) films in (111) and (110) orientation is presented, employing density functional theory calculations. Due to the different coordination of the surface atoms...

Employing first-principles calculations, we perform a systematic study of the electronic properties of thin (one to six bilayers) films of the semimetal bismuth in (111) and (110) orientation. Due to the different coordination of the surface atoms in these two cases, we find a large variation of the conducting properties of the films, ranging from...

The experimental results which point out to the existence of the hydrogen subsystem in solids and a possibility of its excitation by external influence are described. Occupying the equivalent positions inside host metal, hydrogen forms its own subsystem inside a crystal lattice and has vibration frequencies lying outside the phonon spectrum of a cr...

A theoretical study of electronic excitation spectra in Pd and PdH is reported. The calculations were performed with full inclusion of the electron band structure obtained within self-consistent pseudopotential approach. We demonstrate that the complicated Pd electronic structure at the Fermi level is reflected in a numerous peak structure of the e...

Ab initio calculations of the electronic structure of pure Pd, pure Ti, and PdHx and TiHx (x = 1, 2, 3) systems are performed within the local density approximation. It is found that the electronic subsystem of metals containing dissolved hydrogen increases their capacity to absorb the energy of electromagnetic radiation and accumulate it for a lon...

Quantum well states QWSs in ultrathin Bi001 films grown on Si111 -7 7 with thicknesses up to several tens of nanometers were studied by angle-resolved photoemission spectroscopy and first-principles calculations. We observed QWSs at various points in k-space; those located near ¯ are very difficult to distinguish while the QWS peaks at off-normal e...

The surface structure of Bi(110) has been investigated by low-energy electron diffraction intensity analysis and by first-principles calculations. Diffraction patterns at a sample temperature of 110 K and normal incidence reveal a bulk truncated (1x1) surface without indication of any structural reconstruction despite the presence of dangling bonds...

The electronic structure of Bi(001) ultrathin films (thickness 7 bilayers) on Si(111)-7×7 was studied by angle-resolved photoemission spectroscopy and first-principles calculations. In contrast with the semimetallic nature of bulk Bi, both the experiment and theory demonstrate the metallic character of the films with the Fermi surface formed by spi...

Surface states, that show a k-dependent splitting resulting from spin-orbit coupling, show wide similarities to a two-dimensional electron gas in semiconductor heterostructures, where the Rashba-effect lifts the spin-degeneracy of the bands and allows spin-manipulation by an electric field. We discuss the conditions for such a Rashba-effect at meta...

The surface structure of Bi(110) has been investigated by low-energy electron diffraction (LEED) intensity analysis and by first-principles calculations. Diffraction patterns at a sample temperature of 110 K and normal incidence reveal a bulk truncated (1$\times$1) surface without indication of any structural reconstruction despite the presence of...

Bulk and surface states of a clean and Cs-doped surface of a Co film grown on Cu(001) have been studied by spin-resolved photoemission (SR-PE) and compared with band structure calculation results. One-photon (1PPE) and two-photon (2PPE) photoemission spectra from clean Co films are found to be dominated by a peak located at a binding energy of abou...

Most spectroscopic methods for studying the electronic structure of metal surfaces have the disadvantage that either only occupied or only unoccupied states can be probed, and the signal is cut at the Fermi edge. This leads to significant uncertainties, when states are very close to the Fermi level. By performing low-temperature scanning tunneling...

Most spectroscopic methods for studying the electronic structure of metal surfaces have the disadvantage that either only occupied or only unoccupied states can be probed, and the signal is cut at the Fermi edge. This leads to significant uncertainties, when states are very close to the Fermi level. By performing low-temperature scanning tunneling...

Quasiparticle interference patterns measured by scanning tunneling microscopy can be used to study the local electronic structure of metal surfaces and high-temperature superconductors. Here, we show that even in nonmagnetic systems the spin of the quasiparticles can have a profound effect on the interference patterns. On Bi(110), where the surface...

Using first-principles calculations and angle-resolved photoemission, we show that the spin-orbit interaction leads to a strong splitting of the surface-state bands on low-index surfaces of Bi. The dispersion of the states and the corresponding Fermi surfaces are profoundly modified in the whole surface Brillouin zone. We discuss the implications o...

Quasiparticle interference patterns measured by scanning tunneling microscopy (STM) can be used to study the local electronic structure of metal surfaces and high temperature superconductors. Here, we show that even in non-magnetic systems the spin of the quasiparticles can have a profound effect on the interference patterns. On Bi(110), where the...

Using first-principles calculations and angle-resolved photoemission, we show that the spin-orbit interaction leads to a strong splitting of the surface state bands on low-index surfaces of Bi. The dispersion of the states and the corresponding Fermi surfaces are profoundly modified in the whole surface Brillouin zone. We discuss the implications o...

Electrons at noble metal surfaces can be confined within terraces leading to one-dimensional surface states. These can be studied with angle-resolved photoemission from vicinal surfaces with regular arrays of (111)-oriented terraces. Here we show the case of Au(23 23 21), which is vicinal to Au(111) and displays L=56Å wide terraces. The surface sta...

We present a self-consistent calculation of the electronic structure for the (110) surface of equiatomic XTi (X=Fe, Co, and Ni) alloys in the B2 (CsCl) structure. The results were obtained using the film linearized augmented-plane-wave method. We have analyzed the change of the local density of states, the valence electronic charge distribution and...

Electronic structure of the (001) surface of Cu3Au-type ordered alloys Ni3Al, Cu3Pt, and Pt3Ti has been calculated by the self-consistent film linearized augmented-plane-wave method. Effects of the structure geometry and the alloy surface atomic composition on the energy spectrum and character of the surface state localization were investigated. It...

The electronic structure of the FeTi(110) surface has been calculated theoretically using the self-consistent film linearized augmented-plane-wave method. As a result, surface states both above and below the Fermi level have been found. Most of occupied surface states are localized at the atoms of iron, but unoccupied ones are generated by the tita...

The electronic structure of the NiTi(001) surface for both Ni- and Ti-termination has been calculated theoretically using the self-consistent film linearized augmented-plane-wave method. The surface states both above and below the Fermi level have been found. Most of the occupied surface states are localized at the nickel atoms, while almost all th...

The electronic structure of the NiTi(110) surface has been calculated theoretically using the self-consistent film linearized augmented-planewave method. As a result, surface states both above and below the Fermi level have been found. Practically all occupied surface states are localized at the atoms of nickel, but all unoccupied ones are generate...

The electronic structure of Ba(001) and Pb(001) surfaces are calculated in terms of the self-consistent relativistic pseudopotential method. It is shown that taking into account the spin-orbit pseudopotential leads to the appearance of spin-orbit gaps on the barium surface at the and points and to the splitting of the doubly degenerate surface stat...