A5089237237- Semiconductor materials and interfaces
- Microstructure and mechanical properties
- Magnetic Properties and Applications
- Nuclear materials and radiation effects
- Heusler alloys: electronic and magnetic properties
- Rare-earth and actinide compounds
- Crystallography and Radiation Phenomena
- Advanced Materials Characterization Techniques
- Metal and Thin Film Mechanics
- GaN-based semiconductor devices and materials
- Nuclear Materials and Properties
- MXene and MAX Phase Materials
- Advanced Condensed Matter Physics
- High-pressure geophysics and materials
- 2D Materials and Applications
- Magnetic and transport properties of perovskites and related materials
- Electronic and Structural Properties of Oxides
- Copper-based nanomaterials and applications
- Semiconductor materials and devices
- nanoparticles nucleation surface interactions
- Surface and Thin Film Phenomena
- Catalytic Processes in Materials Science
- Nanowire Synthesis and Applications
- Iron-based superconductors research
Karlsruhe Institute of Technology
2018-2024
Stanford Synchrotron Radiation Lightsource
2019
Paul Drude Institute for Solid State Electronics
2017
Using the density functional theory, we study structural and lattice dynamical properties of europium sesquioxide (Eu2O3) in cubic, trigonal, monoclinic phases. The obtained parameters energies Raman modes show a good agreement with available experimental data. Eu-partial phonon states calculated for cubic structure is compared nuclear inelastic scattering data from 20 nm thick Eu2O3 film deposited on YSZ substrate. A small shift spectrum to higher results compressive strain induced by On...
Ferromagnetic Heusler alloys can be used in combination with semiconductors to create spintronic devices. The materials have cubic crystal structures, making it possible grow lattice-matched heterojunctions by molecular beam epitaxy. However, the development of devices is limited difficulty growing epitaxial over metallic surfaces while preventing chemical reactions, a requirement obtain abrupt interfaces and achieve efficient spin-injection tunneling. We solid-phase epitaxy approach...
Reducing the material sizes to nanometer length scale leads drastic modifications of propagating lattice excitations (phonons) and their interactions with electrons magnons.
We report a systematic lattice dynamics study of the technologically important ${\mathrm{Fe}}_{3}\mathrm{Si}$/GaAs heterostructure for ${\mathrm{Fe}}_{3}\mathrm{Si}$ layer thicknesses 3, 6, 8, and 36 monolayers. The Fe-partial phonon density states obtained by nuclear inelastic scattering exhibits up to twofold enhancement low-energy compared bulk material 8 monolayers below. First-principles calculations explain observed effect interface-specific originating from significantly reduced...
The structure and dynamical properties of the Fe$_3$Si/GaAs(001) interface are investigated by density functional theory nuclear inelastic scattering measurements. stability four different atomic configurations Fe$_3$Si/GaAs multilayers is analyzed calculating formation energies phonon dispersion curves. differences in charge density, magnetization, electronic states between examined. Our calculations unveil that magnetic moments Fe atoms tend to align a plane parallel interface, along [110]...
We determined the lattice dynamics of metastable, surface-stabilized $\ensuremath{\alpha}$-phase ${\mathrm{FeSi}}_{2}$ nanoislands epitaxially grown on Si(111) surface with average heights and widths ranging from 1.5 to 20 nm 18 72 nm, respectively. The crystallographic orientation, morphology, local crystal structure were investigated by reflection high-energy electron diffraction, atomic force microscopy, x-ray absorption spectroscopy. Fe-partial phonon density states (PDOS), obtained...
Abstract We report on the fabrication of a novel design GaAs/(In,Ga)As/GaAs radial nanowire heterostructures Si 111 substrate, where, for first time, growth inhomogeneous shells lattice mismatched core results in straight nanowires instead bent. Nanowire bending caused by axial tensile strain induced (In,Ga)As shell GaAs is reversed compressive outer shell. Progressive and reverse addition to evolution during two processes are accessed situ x-ray diffraction. The diameter core, thicknesses...
Self-organized silicide nanowires are considered as building blocks of future nanoelectronics and have been intensively investigated. In nanostructures, the lattice vibrational waves (phonons) deviate drastically from those in bulk crystals, which gives rise to anomalies thermodynamic, elastic, electronic, magnetic properties. Hence a thorough understanding physical properties these materials requires comprehensive investigation dynamics function nanowire size. We performed systematic study...
The spatial confinement of atoms at surfaces and interfaces significantly alters the lattice dynamics thin films, heterostructures multilayers. Ultrathin films with high dielectric constants (high-k) are paramount interest for applications as gate layers in current future integrated circuits. Here we report a study high-k Eu2O3 thicknesses 21.3, 2.2, 1.3, 0.8 nm deposited on YSZ(001). Eu-partial phonon density states (PDOS), obtained from nuclear inelastic scattering, exhibits broadening...
Here we present a combined experimental and ab initio lattice dynamics study of the semiconducting $\ensuremath{\beta}$ phase $\mathrm{Fe}{\mathrm{Si}}_{2}$. A polycrystalline $\ensuremath{\beta}\text{\ensuremath{-}}\mathrm{Fe}{\mathrm{Si}}_{2}$ film was prepared on Si(111) single-crystalline, self-assembled nanorods were grown Si(110) by molecular beam epitaxy. Both types nanostructures obtained annealing precursor structures, an epitaxial Fe in case high-aspect-ratio...
In der vorliegenden Arbeit wird die Gitterdynamik von Nanostrukturen Eisen-Silizium-Verbindungen Fe$_3$Si, $\alpha$-FeSi$_2$, und $\beta$-FeSi$_2$ untersucht. Ein umfassendes Verstandnis des Einflusses einer raumlichen Beschrankung auf Nanometerskala ist Voraussetzung fur Nutzung dieser Materialien in nanoskaligen elektronischen Bauteilen sowie angestrebte gezielte Manipulation Schwingungseigenschaften Nanostrukturen. Monokristalline untersuchten werden mittels Molekularstrahlepitaxie...