A5023684223- Topological Materials and Phenomena
- Graphene research and applications
- Advanced Condensed Matter Physics
- 2D Materials and Applications
- Magnetic properties of thin films
- Planetary Science and Exploration
- Physics of Superconductivity and Magnetism
- Electronic and Structural Properties of Oxides
- Quantum many-body systems
- Iron-based superconductors research
- Diamond and Carbon-based Materials Research
- Astro and Planetary Science
- Atomic and Subatomic Physics Research
- Quantum and electron transport phenomena
- Surface and Thin Film Phenomena
- Quantum, superfluid, helium dynamics
- Magnetic and transport properties of perovskites and related materials
- Theoretical and Computational Physics
- Geomagnetism and Paleomagnetism Studies
- Metallurgical and Alloy Processes
- Heusler alloys: electronic and magnetic properties
- Multiferroics and related materials
- Magnetic Properties of Alloys
- Chalcogenide Semiconductor Thin Films
- Advanced Semiconductor Detectors and Materials
Forschungszentrum Jülich
2016-2024
University of Würzburg
2022-2024
Centre de Biophysique Moléculaire
2013
Centre National de la Recherche Scientifique
2013
Université d'Orléans
2013
The role of the crystal lattice, temperature and magnetic field for spin structure formation in 2D van der Waals magnet Fe5GeTe2 is a key open question. Using Lorentz transmission electron microscopy, we experimentally observe topological structures up to room metastable pre-cooling stable post-cooling phase Fe5GeTe2. Over wide ranges, skyrmionic bubbles form without preferred chirality, which indicative centrosymmetric structure. In phase, these are observable even application an external...
Raman spectroscopy can be used for analysing both mineral and organic phases, thus allowing characterisation of the microbial‐scale geological context as well search possible traces life. This method is therefore very useful in situ planetary exploration missions. Compared with myriad sample preparation techniques available terrestrial laboratories, possibilities during missions on other bodies are extremely limited generally restricted to abrasion rock surfaces or crushing target samples....
The family of topological superconductors derived from $\mathrm{Bi}_{2}\mathrm{Se}_{3}$, $\mathrm{Cu}_x(\mathrm{PbSe})_{5}(\mathrm{Bi}_{2}\mathrm{Se}_{3})_{6}$ is unique in its surface termination a single quintuple layer (QL) the insulator (TI) $\mathrm{Bi}_{2}\mathrm{Se}_{3}$ on an ordinary PbSe. Here, we report combined scanning tunneling microscopy (STM) and density functional theory (DFT) characterization cleaved parent compound $(\mathrm{PbSe})_{5}(\mathrm{Bi}_{2}\mathrm{Se}_{3})_{6}$...
We report on the implementation of Bogoliubov-de Gennes method into JuKKR code [https: //jukkr.fz-juelich.de], an relativistic all-electron, full-potential Korringa-Kohn-Rostoker Green function method, which allows a material-specific description inhomogeneous super-conductors and heterostructures basis density functional theory. describe formalism calculations for s-wave superconductor Nb, potential component materials platform enabling realization Majorana zero modes in field topological...
Abstract Among two-dimensional materials, Fe 3 GeTe 2 has come to occupy a very important place owing its ferromagnetic nature with one of the highest Curie temperatures among known van der Waals materials and potential for hosting skyrmions. In this combined experimental theoretical work, we investigate magnetic bubble domains as well microscopic domain wall profile using spin-polarized scanning tunneling microscopy in combination atomistic spin-dynamics simulations performed parameters...
Multiband effects in hybrid structures provide a rich playground for unconventional superconductivity. We combine two complementary approaches based on density-functional theory (DFT) and effective low-energy model order to investigate the proximity effect Rashba surface state contact with an $s$-wave superconductor. discuss these synergistic DFT analysis at example of Au/Al heterostructure. This allows us predict finite-energy superconducting pairing due interplay Au, hybridization...
The semimetal ${\mathrm{MoTe}}_{2}$ is studied by spin- and angle-resolved photoemission spectroscopy across the centrosymmetry-breaking structural transition temperature of bulk. A three-dimensional spin-texture observed in bulk Fermi surface low temperature, noncentrosymmetric phase that consistent with first-principles calculations. spin texture two types arc are not completely suppressed above temperature. lifetimes quasiparticles forming arcs depend on thermal history lengthen...
Magnetic topological insulators combine two cornerstones of modern solid-state physics: band topology and electron correlations. To understand this class materials, methods that address both itinerant correlated properties are necessary. Here, the authors describe a systematic study Eu-doped Bi${}_{2}$Te${}_{3}$ based on SQUID magnetometry, photoemission, resonant x-ray spectroscopy, density functional theory. The synergy between these tools provides comprehensive picture system, in which...
The ever increasing availability of supercomputing resources led computer-based materials science into a new era high-throughput calculations. Recently, Pizzi et al. [Comp. Mat. Sci. 111, 218 (2016)] introduced the AiiDA framework that provides way to automate calculations while allowing store full provenance complex workflows in database. We present development AiiDA-KKR plugin allows perform large number ab initio impurity embedding based on relativistic full-potential...
Abstract Proximity‐induced superconductivity in hybrid devices of topological insulators and superconductors offers a promising platform for the pursuit elusive its anticipated applications, such as fault‐tolerant quantum computing. To study harness devices, key challenge is realization highly functional material interfaces with suitable superconductor featuring 2‐periodic parity‐conserving transport to ensure superconducting hard‐gap free unpaired electrons, which important Majorana...
Magnetically doped topological insulators may produce novel states of electronic matter, where for instance the quantum anomalous Hall effect state can be realized. Pivotal to this goal is a microscopic control over magnetic state, defined by local structure dopants and their interactions. We report on coupling among Mn or Co atoms adsorbed surface insulator Bi2Te3. Our findings uncover mechanisms exchange between coupled in strong insulators. The combination x-ray circular dichroism ab...
The discovery of Weyl semimetals represents a significant advance in topological band theory. They paradigmatically enlarged the classification materials to gapless systems while simultaneously providing experimental evidence for long-sought fermions. Beyond fundamental relevance, their high mobility, strong magnetoresistance, and possible existence even more exotic effects, such as chiral anomaly, make promising platform develop radically new technology. Fully exploiting potential requires...
Recently it has been shown that surface magnetic doping of topological insulators induces backscattering Dirac states which are usually protected by time-reversal symmetry [Sessi et al., Nat. Commun. 5, 5349 (2014)]. Here we report on quasiparticle interference measurements where, improved Fermi level tuning, strongly focused patterns Mn-doped ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ could be directly observed means scanning tunneling microscopy at 4 K. Ab initio and model calculations reveal...
In this Perspective, we present some important aspects of two fundamental concepts modern spintronics, namely, spin–orbit torque and topology. Although these fields emerged separately in condensed matter physics, spintronics they show a deep connection, which requires further theoretical experimental investigation. The topological features can arise both from momentum space via the wave functions as well real complex magnetic configurations. These manifest themselves unique different...
We develop an accurate nanoelectronic modeling approach for realistic three-dimensional topological insulator nanostructures and investigate their low-energy surface-state spectrum. Starting from the commonly considered four-band $\mathrm{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{p}$ bulk model Hamiltonian ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ family of insulators, we derive new parameter sets ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}, {\mathrm{Bi}}_{2}{\mathrm{Te}}_{3},$...
The quasiparticle interference (QPI) technique is a powerful tool that allows to uncover the structure and properties of electronic material combined with scattering defects at surfaces. Recently this has been pivotal in proving unique surface state topological insulators which manifests itself absence backscattering. In work we derive Green function based formalism for ab initio computation Fourier-transformed QPI images. We show efficiency our new implementation examples forms around...
The proximity effect at a highly transparent interface of an s-wave superconductor (S) and topological insulator (TI) provides promising platform to create Majorana zero modes in artificially designed heterostructures. However, structural chemical issues pertinent such interfaces have been poorly explored so far. Here, we report the discovery Pd diffusion-induced polarization between superconductive Pd1+x(Bi0.4Te0.6)2 (xPBT, 0 ≤ x 1) Pd-intercalated Bi2Te3 by using atomic-resolution scanning...
Interfacing a topological insulator (TI) with an $s$-wave superconductor (SC) is promising material platform that offers the possibility to realize through which Majorana-based topologically protected qubits can be engineered. In our computational study of prototypical SC/TI interface between Nb and Bi$_2$Te$_3$, we identify benefits possible bottlenecks this potential Majorana platform. Bringing in contact TI film induces charge doping from SC TI, shifts Fermi level into conduction band....
With increasing attention in Majorana physics for possible quantum bit applications, a large interest has been developed to understand the properties of interface between an $s$-type superconductor and topological insulator. Up this point analysis was mainly focused on situ prepared Josephson junctions, which consist two coupled single interfaces or ex fabricated devices. In our work we utilize fabrication process, combining selective area growth shadow evaporation allows characterization...
We develop an accurate nanoelectronic modeling approach for realistic three-dimensional topological insulator nanostructures and investigate their low-energy surface-state spectrum. Starting from the commonly considered four-band $\boldsymbol{\mathrm{k\cdot p}}$ bulk model Hamiltonian Bi$_2$Se$_3$ family of insulators, we derive new parameter sets Bi$_2$Se$_3$, Bi$_2$Te$_3$ Sb$_2$Te$_3$. consider a fitting strategy applied to \emph{ab initio} band structures around $\Gamma$ point that...
We propose helical topological superconductivity away from the Fermi surface in three-dimensional time-reversal-symmetric odd-parity multiband superconductors. In these systems, pairing between electrons originating different bands is responsible for corresponding phase transition. Consequently, a pair of Dirac states emerges at finite excitation energies. These are tunable energy by chemical potential and strength band splitting. They protected time-reversal symmetry combined with...