A5082783933- Topological Materials and Phenomena
- Advanced Thermoelectric Materials and Devices
- Chalcogenide Semiconductor Thin Films
- Graphene research and applications
- 2D Materials and Applications
- Magnetic properties of thin films
- Advanced Condensed Matter Physics
- Quantum Dots Synthesis And Properties
- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Quantum many-body systems
- Physics of Superconductivity and Magnetism
- nanoparticles nucleation surface interactions
- Advanced Semiconductor Detectors and Materials
- Perovskite Materials and Applications
- Multiferroics and related materials
- Advanced Thermodynamics and Statistical Mechanics
- Semiconductor Lasers and Optical Devices
- Photonic and Optical Devices
- ZnO doping and properties
- Phase-change materials and chalcogenides
- Iron-based superconductors research
- Terahertz technology and applications
Polish Academy of Sciences
2018-2024
Institute of Physics
2019-2024
National Technical University "Kharkiv Polytechnic Institute"
2013-2024
Johannes Kepler University of Linz
2014-2021
National Technical University of Athens
2016
National Polytechnic School
2006-2010
University of Manitoba
2008-2010
Abstract Commercial magnetic memories rely on the bistability of ordered spins in ferromagnetic materials. Recently, experimental bistable have been realized using fully compensated antiferromagnetic metals. Here we demonstrate a multiple-stable memory device epitaxial MnTe, an counterpart common II–VI semiconductors. Favourable micromagnetic characteristics MnTe allow us to smoothly varying zero-field anisotropic magnetoresistance (AMR) with harmonic angular dependence writing field angle,...
Abstract Entanglement of the spin–orbit and magnetic order in multiferroic materials bears a strong potential for engineering novel electronic spintronic devices. Here, we explore electron spin structure ferroelectric α -GeTe thin films doped with ferromagnetic Mn impurities to achieve its functionality. We use bulk-sensitive soft-X-ray angle-resolved photoemission spectroscopy (SX-ARPES) follow hybridization GeTe valence band dopants. observe gradual opening Zeeman gap bulk Rashba bands...
Antiferromagnetic hexagonal MnTe is a promising material for spintronic devices relying on the control of antiferromagnetic domain orientations. Here we report neutron diffraction, magnetotransport, and magnetometry experiments semiconducting epitaxial thin films together with density functional theory (DFT) calculations magnetic anisotropies. The easy axes moments within basal plane are determined to be along $\ensuremath{\langle}1\overline{1}00\ensuremath{\rangle}$ directions. spin-flop...
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...
Abstract Dirac fermions in condensed matter physics hold great promise for novel fundamental physics, quantum devices and data storage applications. IV-VI semiconductors, the inverted regime, have been recently shown to exhibit massless topological surface protected by crystalline symmetry, as well massive bulk fermions. Under a strong magnetic field (B), both states are quantized into Landau levels that disperse B 1/2 thus difficult distinguish. In this work, magneto-optical absorption is...
Negative longitudinal magnetoresistance (NLMR) is shown to occur in topological materials the extreme quantum limit, when a magnetic field applied parallel excitation current. We perform pulsed and dc measurements on Pb1−xSnxSe epilayers where state can be chemically tuned. The NLMR observed state, but suppressed becomes positive system trivial. In material, lowest N=0 conduction Landau level disperses down energy as function of increasing field, while valence upwards. This anomalous...
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:...
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...
The control of the electron spin by external means is a key issue for spintronic devices. Using spin- and angle-resolved photoemission spectroscopy (SARPES) with three-dimensional detection, we demonstrate operando electrostatic manipulation in ferroelectric GeTe multiferroic Ge1-xMnxTe. We not only first time Rashba semiconductors due to polarization reversal, but are also able follow switching pathway detail, show gain Rashba-splitting strength under fields. In Ge1-xMnxTe SARPES reveals...
Despite several theoretical predictions regarding the physics and application of quantum wells (QWs) topological crystalline insulators (TCI), no quantized charge transport via helical or chiral edge states has been experimentally demonstrated for such a class systems. In this study, we report here on successful growth by molecular beam epitaxy high quality Pb$_{1-x}$Sn$_{x}$Se:Bi/Pb$_{1-y}$Eu$_{y}$Se QWs with $x = 0.25$ $y 0.1$, their magnetotransport characterization as function QW...
We report on the thickness d dependences of Seebeck coefficient, electrical conductivity, and Hall coefficient PbTe PbS epitaxial thin films (d=5–200 nm), prepared by thermal evaporation in vacuum deposition (001) KCl substrates. The oxidation air at 300 K leads to a sign inversion carrier type from n p with d⩽125 110 nm for PbS, respectively. observed are interpreted terms compensating acceptor states created oxygen film surface.
Antiferromagnetic coupling between ferromagnetic layers has been observed for the first time in all-semiconductor superlattice structure EuS/PbS(001), by neutron scattering and magnetization measurements. Spin-dependent band effects are invoked to explain possible origin strength of coupling.
Metal-halide-perovskites revolutionized the field of thin-film semiconductor technology, due to their favorable optoelectronic properties and facile solution processing. Further improvements perovskite devices require structural coherence on atomic scale. Such perfection is achieved by epitaxial growth, a method that based use high-end deposition chambers. Here growth enabled via ≈1000 times cheaper device, single nozzle inkjet printer. By printing, single-crystal micro- nanostructure arrays...
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....
Abstract When a Dirac fermion system acquires an energy-gap, it is said to have either trivial (positive energy-gap) or non-trivial (negative topology, depending on the parity ordering of its conduction and valence bands. The regime identified by presence topological surface edge-states dispersing in energy gap bulk attributed non-zero index. In this work, we show that such indices can be determined experimentally via accurate measurement effective velocity massive fermions. We demonstrate...
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...
This paper uses light polarization dependent spin-resolved photoemission and ab initio calculations to show that bulk states of ferroelectric GeTe are fully spin polarized, making this material a promising candidate for room temperature spintronics applications.
Extrema were observed in the film thickness d dependence of various thermoelectric parameters (Seebeck coefficient S, electrical conductivity σ, Hall RH, charge carrier mobility μ, and power factor P) epitaxial PbTe/(001) KCl thin films prepared by thermal evaporation vacuum protected from oxidation an EuS layer. We attribute extrema properties high values μ P at d≈50 nm to percolation transition island-like a continuous self-organization islands, which can occur not only quantum dot...
Many conductors, including recently studied Dirac materials, show saturation of coherence length on decreasing temperature. This surprising phenomenon is assigned to external noise, residual magnetic impurities, or two-level systems specific noncrystalline solids. Here, by considering the SnTe-class compounds as an example, we theoretically that breaking mirror symmetry deteriorates Berry's phase quantization, leading additional dephasing in weak-antilocalization magnetoresistance (WAL-MR)....
In magnetic topological phases of matter, the quantum anomalous Hall (QAH) effect is an emergent phenomenon driven by ferromagnetic doping, proximity effects and strain engineering. The realization QAH states with multiple dissipationless edge surface conduction channels defined a Chern number $\mathcal{C}\geq1$ was foreseen for ferromagnetically ordered SnTe class crystalline insulators (TCIs). From magnetotransport measurements on Sn$_{1-x}$Mn$_{x}$Te ($0.00\leq{x}\leq{0.08}$)(111)...
Optical in-well pumped mid-infrared vertical external cavity surface emitting lasers based on PbTe quantum wells embedded in CdTe barriers are realized. In contrast to the usual ternary barrier materials of lead salt such as PbEuTe PbSrTe, combination narrow-gap with wide-gap offers an extremely large carrier confinement, preventing charge leakage from wells. addition, optical pumping can be achieved cost effective and readily available near infrared lasers. Free absorption, which is a...