A5060716796- Heusler alloys: electronic and magnetic properties
- Rare-earth and actinide compounds
- Pregnancy and preeclampsia studies
- Urinary Bladder and Prostate Research
- Pelvic floor disorders treatments
- Magnetic properties of thin films
- Iron-based superconductors research
- MXene and MAX Phase Materials
- Urological Disorders and Treatments
- Birth, Development, and Health
- Topological Materials and Phenomena
- Magnetic and transport properties of perovskites and related materials
- Inorganic Chemistry and Materials
- 2D Materials and Applications
- Magnetic Properties of Alloys
- Quantum and electron transport phenomena
- Ureteral procedures and complications
- Intermetallics and Advanced Alloy Properties
- Surface and Thin Film Phenomena
- Electrolyte and hormonal disorders
- Cell Image Analysis Techniques
- Prenatal Screening and Diagnostics
- Assisted Reproductive Technology and Twin Pregnancy
- Health and Medical Studies
- Graphene research and applications
Johannes Gutenberg University Mainz
2007-2016
Max Planck Society
2012
Universitäts Frauenklinik
1989-2009
Frauenklinik Heidelberg
1991
University of Applied Sciences Mainz
1985-1987
University Medical Center of the Johannes Gutenberg University Mainz
1987
In this Letter we show that superconducting ${\mathrm{Fe}}_{1.01}\mathrm{Se}$ undergoes a structural transition at 90 K from tetragonal to an orthorhombic phase but nonsuperconducting ${\mathrm{Fe}}_{1.03}\mathrm{Se}$ does not. High resolution electron microscopy low temperatures further reveals unexpected additional modulation of the crystal structure involves displacements Fe atoms, and composition shows different, complex nanometer-scale modulation. Finally, magnetism is not driving force...
Half-Heusler compounds are an impressive class of materials with a huge potential for different applications such as future energy and spintronics. The semiconducting Heusler can be identified by the number valence electrons. band gap tuned between 0 4 eV electronegativity difference constituents. Magnetism introduced in these using rare-earth elements, manganese or 'electron' doping. Thus, there is great interest fields thermoelectrics, solar cells diluted magnetic semiconductors....
Band Jahn–Teller type structural instabilities of cubic Mn2YZ Heusler compounds causing tetragonal distortions can be predicted by ab initio band-structure calculations. This allows for identification new materials with tunable magnetic and properties that satisfy the demands spintronic applications, such as in spin-transfer torque-based devices. represent a remarkable class more than 1500 members. While they have been known long time,1 it is only recent years wide range their extraordinary...
Abstract Heusler compounds are promising materials in many fields of contemporary research. The spectrum their possible applications ranges from magnetic and magneto‐mechanical over semiconductors thermoelectrics to superconductors. An important feature the is possibility controlling valence electron concentration by partial substitution elements. On other hand, properties also depend on degree ordering crystal structure. In general, crystallize Cu 2 MnAl‐type structure but cases certain...
Topological insulators (TIs) are a new quantum state of matter which have gapless surface states inside the bulk energy gap. Starting with discovery two dimensional TIs, HgTe-based wells, many topological materials been theoretically predicted and experimentally observed. Currently known TI can possibly be classified into families, HgTe family Bi2Se family. The signatures found in electronic structure also cause these to excellent thermoelectric materials. On other hand, topologically...
Co$_2$FeSi crystallizes in the ordered L2$_1$ structure as proved by X-ray diffraction and M\"o\ss bauer spectroscopy. The magnetic moment of was measured to be about $6\mu_B$ at 5K. Magnetic circular dichroism spectra excited soft X-rays (XMCD) were taken determine element specific moments Co Fe. Curie temperature with different methods ($1100\pm20$)K. found Heusler compound well half-metallic ferromagnet highest temperature.
We present a rational design scheme intended to provide stable high spin polarization at the interfaces of magnetoresistive junctions by fulfilling criteria structural and chemical compatibilities interface. This can be realized joining semiconducting half-metallic Heusler materials with similar structures. The first-principles calculations verify that interface remains if nearest layers effectively form material properties intermediately between surrounding bulk parts. leads simple rule for...
Heavy stuff: Topological insulators are formed of heavy atoms and host special surface or edge states. The electronic structure is characterized by a Dirac cone within bulk band gap (see picture) that generated strong spin-orbit coupling. A chemist's perspective in terms bonds, bands, symmetry, nuclear charge provided.
Abstract Compounds with LiAlSi (half‐Heusler) and LiGaGe structure types have been investigated by means of band calculations. The type is known as the half‐Heusler type, whereas a closely related hexagonal variant. A remarkable feature some XYZ compounds 8 18 valence electrons is, that despite being composed only metallic elements, they are semiconductors. More than 100 semiconducting within these known. an additional degree freedom, namely puckering layers. These can become at certain...
This work reports on the experimental investigation of wide band gap compounds LiMgZ (Z = P, As, Sb), which are promising candidates for opto-electronics and anode materials Lithium batteries. The crystallize in cubic (C1_b) MgAgAs structure (space group F-43m). polycrystalline samples were synthesized by solid state reaction methods. X-ray neutron diffraction measurements show a homogeneous, single-phased samples. electronic properties studied using direct current (DC) method. Additionally...
The long and short range order of chemically prepared Co2FeGa Heusler nanoparticles with various sizes are determined by x-ray diffraction (XRD) extended absorption fine structure (EXAFS) spectroscopy. Specifically, EXAFS fittings reveal the size dependent crystal type nanoparticles. With decreasing particle size, degree L21 in decreases probability B2 disorder increases simultaneously. consequences antisite on correlated also discussed.
Electron spin resonance measurements in ${\text{EuFe}}_{2}{\text{As}}_{2}$ single crystals revealed an absorption spectrum of a with Dysonian line shape. Above the spin-density wave (SDW) transition at ${T}_{\text{SDW}}=190\text{ }\text{K}$ spectra are isotropic and Eu spins relax via conduction electrons resulting Korringa-type increase linewidth. Below ${T}_{\text{SDW}}$, distinct anisotropy develops relaxation behavior changes drastically into one characteristic properties magnetic...
Topologische Isolatoren bestehen aus schweren Atomen und besitzen spezielle Oberflächen- oder Kantenzustände. Ihre elektronische Struktur wird durch einen Dirac-Kegel in der Volumenphasen-Bandlücke charakterisiert, eine starke Spin-Bahn-Kopplung entsteht (siehe Bild). Aus Sicht eines Chemikers werden einfache Regeln unter Verwendung von Bindungen, Bändern, Symmetrie Kernladungen vorgeschlagen.
The XYZ half-Heusler crystal structure can conveniently be described as a tetrahedral zinc blende YZ which is stuffed by slightly ionic X species. This description well suited to understanding the electronic of semiconducting 8-electron compounds such LiAlSi (formulated Li+[AlSi]−) or 18-electron TiCoSb Ti4+[CoSb]4−). basis for this that [AlSi]− (with same electron count Si2) and [CoSb]4− (the GaSb) are both, structurally electronically, semiconductors. half-metallic ferromagnets in type...
In this contribution, we report the chemical synthesis of carbon coated, silica supported Co2FeGa (Co2FeGa-SiO2@C) nanocomposite particles. The particle size particles can be tuned by varying amount supports. dependences crystal structure and magnetic properties on have been investigated synchrotron radiation based X-ray diffraction (XRD), absorption fine (XAFS) spectroscopy, transmission electron microscope (TEM), 57Fe Mössbauer superconducting quantum interference device (SQUID)....
Abstract Fe 2 CoGa Heusler nanoparticles are synthesized by a chemical method. The structure and magnetic properties of investigated x-ray diffraction, extended absorption fine Mössbauer spectroscopy. crystal is described the X-type (prototype: Li AgSb). Magnetic measurements reveal presence small lower moments compared with theoretically predicted values.
Heusler nanocrystals, i.e., compounds with dimensions in nanometer range are promising materials for next-generation spin-related devices. Recently, we have developed a chemical approach to prepare L21 ordered nanoparticles and characterized their size-related structure magnetic properties. In this work, effect of precursor composition is investigated terms importance controlling the phase Co2FeGa nanoparticles. The formation evidenced by combining X-ray diffraction (XRD) extended absorption...
Decisive for urethral closure under stress is an increase in intraurethral pressure. This pressure significantly affected by tonus, passive transmission and reflex transmission. Approximately half of the tonus produced striated sphincter muscles (Rud et al. 1981; Tanagho 1979).
Copper doping of FeSe destroys its superconductivity at ambient pressure, even low levels. Here we report the pressure-dependent transport and structural properties Fe${}_{1.01\ensuremath{-}x}$Cu${}_{x}$Se with 3$%$ 4$%$ Cu find that is restored. Metallic resistivity behavior, absent in Cu-doped FeSe, also At pressure 1.5 GPa, seen 6 K for doping, somewhat lower than 8 ${T}_{c}$ undoped FeSe. reaches maximum 31.3 7.8 superconducting temperature material under (${T}_{c}$ max 37 K) but still...