A5086209872- Magnetic properties of thin films
- Surface and Thin Film Phenomena
- Advanced Chemical Physics Studies
- Magnetic and transport properties of perovskites and related materials
- Quantum and electron transport phenomena
- Advanced Condensed Matter Physics
- ZnO doping and properties
- nanoparticles nucleation surface interactions
- Photonic Crystals and Applications
- Electronic and Structural Properties of Oxides
- Physics of Superconductivity and Magnetism
- Electron and X-Ray Spectroscopy Techniques
- Multiferroics and related materials
- Graphene research and applications
- Rare-earth and actinide compounds
- Molecular Junctions and Nanostructures
- Optical Coatings and Gratings
- Silicon Nanostructures and Photoluminescence
- Magnetism in coordination complexes
- Chemical and Physical Properties of Materials
- Photonic and Optical Devices
- Copper-based nanomaterials and applications
- X-ray Diffraction in Crystallography
- Theoretical and Computational Physics
- Ferroelectric and Piezoelectric Materials
Martin Luther University Halle-Wittenberg
2012-2023
Leipzig University
1984-2013
Luther University
1984-2012
Max Planck Institute of Microstructure Physics
1996-2003
University of Turku
2003
Wittenberg University
1999
Institute for High Pressure Physics
1998
Forschungszentrum Jülich
1998
Russian Academy of Sciences
1997
We have investigated the magnetic properties of pure ZnO thin films grown under ${\text{N}}_{2}$ pressure on $a$-, $c$-, and $r$-plane ${\text{Al}}_{2}{\text{O}}_{3}$ substrates by pulsed-laser deposition. The substrate temperature were varied from room to $570\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$ 0.007 1.0 mbar, respectively. bare SQUID magnetometry. $c$- $a$-plane did not show significant ferromagnetism. However, showed reproducible ferromagnetism at 300 K when...
The magnetic interlayer coupling in La0.7Sr0.3MnO3/SrRuO3 superlattices was investigated. High quality with ultrathin La0.7Sr0.3MnO3 and SrRuO3 layers were fabricated by pulsed laser deposition. grew coherently Mn/Ru intermixing restricted to about one interfacial monolayer. Strong antiferromagnetic depended delicately on magnetocrystalline anisotropy at interfaces. Ab initio calculations elucidated that the is mediated Mn-O-Ru bond. theoretical allowed for a quantitative correlation between...
This work probes the relevance of oxygen vacancies in formation local ferromagnetic coupling between Fe ions at octahedral sites zinc ferrites. gives rise to a ferrimagnetic ordering with Curie temperatures above room temperature an otherwise antiferromagnetic compound. conclusion is based on experimental results from x-ray magnetic circular dichroism measurements $\mathrm{Fe}{\mathrm{L}}_{2,3}$ edges and magnetization performed ferrites, nanoparticles, films, different cation distributions...
High-intensity THz lasers allow for the coherent excitation of individual phonon modes. The ultrafast control emergent magnetism by means phonons opens up new tuning mechanisms functional materials. While theoretically predicted magnetic moments are tiny, recent experiments hint towards a significant magnetization in various To explain these phenomena, we derive coupling mechanism between angular momentum and electron spin. This introduces transient level splitting spin-up spin-down channels...
We present systematic ab initio calculations for the magnetic moments of 3d, 4d, and 5d transition-metal impurities as single adatoms on (001) surfaces Pd Pt. Large are found all 3d except Sc Ti, which nonmagnetic. Among 4d Mo, Tc, Ru W, Re, Os have large moments. Also adatom-induced magnetization Pt is investigated. compare our results with former adsorbate atoms Cu Ag monolayers these substrates.
An ab initio study of magnetic exchange interactions in antiferromagnetic and strongly correlated 3d transition metal monoxides is presented. Their electronic structure calculated using the local self-interaction correction approach, implemented within Korringa-Kohn-Rostoker band method, which based on multiple scattering theory. The Heisenberg constants are evaluated with force theorem. Based these corresponding Neel temperatures T_N spin wave dispersions calculated. obtained mean field...
Using a first-principles Green's function approach we study magnetic properties of the binary tetradymite chalcogenides ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$, and ${\mathrm{Sb}}_{2}{\mathrm{Te}}_{3}$. The coupling between transition-metal impurities is long range, extends beyond quintuple layer, decreases with increasing number $d$ electrons per $3d$ atom. We find two main mechanisms for interaction in these materials: indirect exchange mediated by free...
The theoretical treatment of complex oxide structures requires a combination efficient methods to calculate structural, electronic, and magnetic properties, due special challenges such as strong correlations disorder. In terms multicode approach, this study combines various complementary first‐principles based on density functional theory exploit their specific strengths. Pseudopotential methods, known for giving reliable forces total energies, are used structural optimization. optimized...
By using an N-body potential scheme constructed by fitting the interaction parameters to accurate first-principles calculations, we investigate structural stability of Co atoms and clusters deposited on Cu(100). We found that prefer be embedded inside substrate, in a way compatible with formation surface alloy observed experimentally. Enhanced is achieved when are preformed cluster uppermost layer substrate. islands best stabilized they concur complete islands, promoting layer-by-layer growth.
We propose a simplified version of self-interaction corrected local spin-density (SIC-LSD) approximation, based on multiple scattering theory, which implements correction locally, within the KKR method. The aspect this new SIC-LSD method allows for description crystal potentials vary from site to in random fashion and calculation physical quantities averaged over ensembles such using coherent potential approximation. This facilitates applications SIC alloys pseudoalloys could describe...
From the basis of ab initio electronic structure calculations which include effects thermally excited magnetic fluctuations, we predict Mn-stabilized cubic zirconia to be ferromagnetic above 500 K. We find this material, is well known both as an imitation diamond and a catalyst, half-metallic with majority minority spin Mn impurity states lying in zirconia's wide gap. The concentration can exceed 40%. high-${T}_{C}$ ferromagnetism robust oxygen vacancy defects how impurities are distributed...
In recent years, the number of nominally nonmagnetic solids showing magnetic order induced by some kind defect has increased continuously. From single element material graphite to several covalently bonded compounds, influence defects like vacancies and/or ad-atoms on triggering attracted interest experimentalists and theoreticians. We review discuss main theoretical approach as well recently obtained experimental evidence based different methods that support existence defect-induced...
One of the most promising candidates for construction ultrahigh-density storage media is low-dimensional atomic-scale magnetic nanostructures exhibiting bi- or multistability. Here we propose a novel route locally controlling and switching magnetism in such nanostructures. Our ab initio studies reveal that externally applied electric field can be used this purpose.
Density functional theory and scanning tunneling microscopy are used to resolve the long-range adsorbate interactions between Co adatoms on Cu(111), caused by quantum interference of surface-state electrons. Our calculations experimental results in very good quantitative agreement. We reveal effect surface state electrons adatom motion, leading self-assembly one-dimensional structures metal surfaces.
Magnetic states of fcc disordered substitutional alloys ${\mathrm{Fe}}_{x}{\mathrm{Cu}}_{1\ensuremath{-}x}$ have been studied by the Korringa-Kohn-Rostoker method within coherent-potential approximation. Total-energy calculations with fixed-spin-moment procedure used to investigate behavior magnetic phases an increasing concentration Cu. These investigations are restricted ferromagnetic states. The ground state alloy is highly sensitive equilibrium volume unit cell. nonmagnetic at lattice...
We demonstrate that a size-dependent mesoscopic mismatch exists in homoepitaxy, which has strong impact on the morphology of islands and substrate. Atomic scale calculations for double layer Cu Cu(111) reveal strain relaxations both substrate strongly influence shape can effect details atomic motion near island.
Self-consistent first-principles calculations based on the molecular-orbital theory and Korringa-Kohn-Rostoker Green's-function method have been used to demonstrate that magnetism of Rh clusters can be altered by either modifying their structure or depositing them a suitable substrate. This ability alter magnetic properties also significant effect chemical reactivity, thus linking field catalysis atomically engineered materials.
The electronic and magnetic structure of bulk NiO the NiO(100) surface is calculated using density-functional theory (DFT) in local-spin-density (LSD) approximation including self-interaction corrections. We calculate exchange coupling constants at show that case they agree better with experiment than standard DFT calculations LSD approximation. develop a model for interactions discuss how change from to bulk.
The structural phase transitions and the fundamental band gaps of ${\text{Mg}}_{x}{\text{Zn}}_{1\ensuremath{-}x}\text{O}$ alloys are investigated by detailed first-principles calculations in entire range Mg concentrations $x$, applying a multiple-scattering theoretical approach (Korringa-Kohn-Rostoker method). Disordered treated within coherent-potential approximation. for various crystal phases have given rise to diagram good agreement with experiments other approaches. transition from...
The exchange coupling between single 3d magnetic adatoms (Cr, Mn, Fe, and Co) adsorbed on a Cu(001) surface Cr STM tip is studied with ab initio calculations. We demonstrate that the spin direction of can be controlled by varying tip-substrate distance, sign energy determined competition direct indirect interactions adatom. Based spin-dependent transport calculations, we find magnetoresistance about 70% at short distances.
In order to gain insight into the so-called d0-magnetic properties of defective ZnO we have carried out first principles calculations on various types defects formed by intrinsic and doped atoms as well pairs them. The include N H. agreement with previous works find several possibilities create magnetic especially hole formation. Our results also show that two which are in vicinity each other when isolated, general become non-magnetic if one them is acceptor-like donor-like. Furthermore,...