A5005868834- Topological Materials and Phenomena
- Metal and Thin Film Mechanics
- Diamond and Carbon-based Materials Research
- Silicon and Solar Cell Technologies
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and interfaces
- Advanced materials and composites
- 2D Materials and Applications
- Graphene research and applications
- Thin-Film Transistor Technologies
- Advanced Semiconductor Detectors and Materials
- Electronic and Structural Properties of Oxides
- Advanced Condensed Matter Physics
- Magnetic properties of thin films
- Chalcogenide Semiconductor Thin Films
- Semiconductor materials and devices
- Quantum Dots Synthesis And Properties
- Magnetic and transport properties of perovskites and related materials
- Phase-change materials and chalcogenides
- ZnO doping and properties
- GaN-based semiconductor devices and materials
- Copper Interconnects and Reliability
- Silicon Nanostructures and Photoluminescence
- Heusler alloys: electronic and magnetic properties
- Magnetic Properties and Applications
Masaryk University
2016-2025
Central European Institute of Technology
2013-2022
Brno University of Technology
2018-2022
Czech Academy of Sciences, Institute of Physics
2017-2020
Central European Institute of Technology – Masaryk University
2011-2020
Czech Academy of Sciences
2017-2020
University of Houston
2005-2010
Abstract Magnetic doping is expected to open a band gap at the Dirac point of topological insulators by breaking time-reversal symmetry and enable novel phases. Epitaxial (Bi 1− x Mn ) 2 Se 3 prototypical magnetic insulator with pronounced surface ∼100 meV. We show that this neither due ferromagnetic order in bulk or nor local moment Mn, making system unsuitable for realizing further does not affect inverted remains topologically nontrivial. suggest strong resonant scattering processes cause...
Ferromagnetic topological insulators exhibit the quantum anomalous Hall effect that might be used for high precision metrology and edge channel spintronics. In conjunction with superconductors, they could host chiral Majorana zero modes which are among contenders realization of qubits. Recently, it was discovered stable 2+ state Mn enables formation intrinsic magnetic A1B2C4 stoichiometry. However, first representative, MnBi2Te4, is antiferromagnetic 25 K N\'eel temperature strongly n-doped....
Optical reflectivity experiments on Cd${}_{3}$As${}_{2}$ indicate the presence of Kane electrons rather than Dirac fermions in this material. The results contradict those from recent ARPES experiments, but agree with STM results.
Altermagnetic (AM) materials exhibit non-relativistic, momentum-dependent spin-split states, ushering in new opportunities for spin electronic devices. While the characteristics of spin-splitting are documented within framework non-relativistic group symmetry, there is limited exploration inclusion relativistic symmetry and its impact on emergence a novel band structure. This study delves into intricate structure an AM material, α-MnTe. Employing temperature-dependent angle-resolved...
Epitaxial growth of topological insulator bismuth telluride by molecular beam epitaxy onto BaF2 (111) substrates is studied using Bi2Te3 and Te as source materials. By changing the flux composition, different stoichiometric phases are obtained, resulting in high quality Bi1Te1 epilayers shown Raman spectroscopy high-resolution X-ray diffraction. From reciprocal space mapping, residual strain, well size coherently scattering domains deduced. The modes for two identified dielectric functions...
The topological properties of lead-tin chalcogenide crystalline insulators can be widely tuned by temperature and composition. It is shown that bulk Bi doping epitaxial Pb1-xSnxTe (111) films induces a giant Rashba splitting at the surface level. Tight binding calculations identify their origin as Fermi level pinning trap states surface. A novel class (TIs), called (TCIs), has been recently predicted1, 2 experimentally demonstrated for SnTe,2, 3 Pb1-xSnxTe,4, 5 Pb1-xSnxSe.6 In these IV–VI...
Despite intensive investigations of Bi2Se3 in past few years, the size and nature bulk energy band gap this well-known 3D topological insulator still remain unclear. Here we report on a combined magneto-transport, photoluminescence infrared transmission study Bi2Se3, which unambiguously shows that material is direct reaches E g = (220 ± 5) meV at low temperatures.
Topological insulators constitute a new phase of matter protected by symmetries. Time-reversal symmetry protects strong topological the Z2 class, which possess an odd number metallic surface states with dispersion Dirac cone. crystalline are merely individual crystal symmetries and exist for even cones. Here, we demonstrate that Bi-doping Pb1-x Sn x Se (111) epilayers induces quantum transition from insulator to insulator. This occurs because lifts fourfold valley degeneracy gap at [Formula:...
We report on Landau-level spectroscopy of an epitaxially grown thin film the topological insulator <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:msub><a:mi>Sb</a:mi><a:mn>2</a:mn></a:msub><a:msub><a:mi>Te</a:mi><a:mn>3</a:mn></a:msub></a:mrow></a:math>, complemented by ellipsometry and magnetotransport measurements. The observed response suggests that <b:math...
The structure and composition of Bi 2 Te 3−δ topological insulator layers grown by molecular beam epitaxy is studied as a function flux composition. It demonstrated that, depending on the Te/Bi 3 ratio, different layer compositions are obtained corresponding to deficit δ varying between 0 1. On basis X-ray diffraction analysis theoretical description using random stacking model, it shown that for ≥ epilayers described well Te–Bi–Te–Bi–Te quintuple Bi–Bi bilayers sharing same basic hexagonal...
We show that in manganese-doped topological insulator bismuth telluride layers, Mn atoms are incorporated predominantly as interstitials the van der Waals gaps between quintuple layers and not substitutionally on Bi sites within layers. The structural properties of epitaxial with concentration up to 13% studied by high-resolution x-ray diffraction, evidencing a shrinking both in-plane out-of plane lattice parameters increasing content. Ferromagnetism sets for contents around 3% Curie...
Qualitative differences between nanoparticle aggregates and chain bound clusters the structural impact on properties of adsorbing solution blended polymer nanocomposites.
We present a detailed x-ray diffraction study of the structural evolution epitaxial FeRh films across temperature-driven phase transition between antiferromagnetic and ferromagnetic order. grown onto MgO, W/MgO, $\mathrm{A}{\mathrm{l}}_{2}{\mathrm{O}}_{3}$ substrates show qualitatively different lattice distortions (tetragonal vs rhombohedral), while keeping sharp above room temperature. Temperature-dependent reciprocal space mapping reveals phase-specific crystal structure, giving access to...
Unlike TiO 2 and SnO , room temperature ferromagnetism in pristine ZnO films does not appear to originate from oxygen vacancies.
Abstract Structure inversion asymmetry is an inherent feature of quantum confined heterostructures with non‐equivalent interfaces. It leads to a spin splitting the electron states and strongly affects electronic band structure. The effect particularly large in topological insulators because surface are extremely sensitive Here, first experimental observation theoretical explication this reported for crystalline insulator wells made Pb 1− x Sn Se by y Eu barriers on one side vacuum other....
We report results of Raman and ellipsometric spectroscopy the topological insulators Bi2Te3 Bi2Se3 grown by molecular beam epitaxy on BaF2 (111) substrates. Surfaces interfaces films are probed scattering from front back sides samples, which is possible owing to transparent substrate. Surface modifications induced intense illumination with exciting laser light have been detected, excess tellurium at surface during after exposure. also data for thin epilayers containing a fractional number...
We have investigated the optical properties of thin films topological insulators Bi$_{2}$Te$_{3}$, Bi$_{2}$Se$_{3}$ and their alloys Bi$_2$(Te$_{1-x}$Se$_x$)$_3$ on BaF$_{2}$ substrates by a combination infrared ellipsometry reflectivity in energy range from 0.06 to 6.5 eV. For onset interband absorption Bi$_2$Se$_3$, after correction for Burstein-Moss effect, we find value direct bandgap $215\pm10$ meV at 10 K. Our data supports picture that Bi$_2$Se$_3$ has band gap located $\Gamma$ point...
We report the detailed optical properties of Cd$_3$As$_2$ crystals in a wide parameter space: temperature, magnetic field, carrier concentration and crystal orientation. investigate high-quality synthesized by three different techniques. In all studied samples, independently how they were prepared treated before experiments, our data indicate conspicuous fluctuations density (up to 30%). These charge puddles have characteristic scale 100 $\mu$m, become more pronounced at low temperatures,...
Ferroelectric $\ensuremath{\alpha}$-GeTe is unveiled to exhibit an intriguing multiple nontrivial topology of the electronic band structure due existence triple-point and type-II Weyl fermions, which goes well beyond giant Rashba spin splitting controlled by external fields as previously reported. Using spin- angle-resolved photoemission spectroscopy combined with ab initio density functional theory, unique texture around triple point caused crossing one spin-degenerate two spin-split bands...
We propose the ion-beam sputtering deposition providing Ti thin films of desired crystallographic orientation and smooth surface morphology not obtainable with conventional techniques such as magnetron vacuum evaporation. The was provided by argon broad ion beams generated a Kaufman source. In order to achieve optimal properties film, we investigated deposited on an amorphous thermal silicon dioxide using X-ray diffraction, atomic force microscopy. have optimized conditions for growing only...