A5032388987- Magnetic properties of thin films
- Topological Materials and Phenomena
- Graphene research and applications
- Anodic Oxide Films and Nanostructures
- 2D Materials and Applications
- Magnetic Properties and Applications
- Nanoporous metals and alloys
- Characterization and Applications of Magnetic Nanoparticles
- Physics of Superconductivity and Magnetism
- Quantum and electron transport phenomena
- Advanced Condensed Matter Physics
- Electrodeposition and Electroless Coatings
- Microstructure and mechanical properties
- Metallic Glasses and Amorphous Alloys
- Iron oxide chemistry and applications
- Magnetic Properties and Synthesis of Ferrites
- Nanopore and Nanochannel Transport Studies
- Theoretical and Computational Physics
Universität Hamburg
2012-2017
Abstract NbP is a recently realized Weyl semimetal (WSM), hosting points through which conduction and valence bands cross linearly in the bulk exotic Fermi arcs appear. The most intriguing transport phenomenon of WSM chiral anomaly-induced negative magnetoresistance (NMR) parallel electric magnetic fields. In intrinsic lie far from energy, making magneto-transport elusive. Here, we use Ga-doping to relocate energy sufficiently close W2 points, for different surfaces are verified by resultant...
Nickel-rich NiFe nanowires with well-controlled diameters and compositions are fabricated in various porous alumina templates by using a pulsed electrochemical deposition technique. The average pore diameter of the is tuned either coating walls thin silica layers an atomic layer (ALD) technique or applying chemical widening process. composition alloy controlled varying frequency pulse. coercivity nanowire array influenced its texture amount iron content alloy. effective field saturation...
Magnetic properties of cylindrical Ni80Fe20 nanowires with modulated diameters are investigated theoretically as a function their geometrical parameters and compared those produced inside the pores anodic alumina membranes by pulsed electrodeposition. We observe that reverse magnetization via nucleation propagation vortex domain wall. The system begins generating domains in nanowire ends transition region between two segments to minimize magnetostatic energy generated surfaces perpendicular...
Weyl semimetals are often considered the 3D-analogon of graphene or topological insulators. The evaluation quantum oscillations in these systems remains challenging because there multiple conduction bands. We observe de Haas-van Alphen with several frequencies a single crystal semimetal niobium phosphide. For each fundamental axis, we can fit raw data to superposition sinusoidal functions, which enables us calculate characteristic parameters all individual bulk bands using Fourier transform...
Straight magnetic nanowires composed of nickel and permalloy segments having different diameters are synthesized using a promising approach. This approach involves the controlled electrodeposition each material into specially designed diameter-modulated porous alumina templates. Standard templates exposed to pore widening followed by protective coating wall with ultrathin silica further anodization. Micromagnetic simulations employed investigate process magnetization reversal in fabricated...
Segmented magnetic nanowires are a promising route for the development of three dimensional data storage techniques. Such devices require control coercive field and coupling mechanisms between individual elements. In our study, we investigate electrodeposited nanomagnets within host templates using vibrating sample magnetometry observe strong dependence nanowire length (25 nm-5 μm) diameter (25-45 nm). A transition from magnetization reversal through coherent rotation to domain wall...
The first-order reversal curve (FORC) method can be used to extract information about the interaction and switching field distribution of ferromagnetic nanowire arrays, yet it remains challenging acquire reliable values. Within ordered pores anodic alumina templates we electrochemically synthesize eight different Ni x Co1?x samples with varying between 0.05 1. FORC diagrams are acquired using vibrating sample magnetometry. By dissolving template magneto-optical Kerr effect, measure...
Magnetite (Fe3O4) of high quality was prepared by combining atomic layer deposition (ALD) with a subsequent thermal reduction process. The process in hydrogen atmosphere investigated situ x-ray diffraction studies as function temperature. A complete to Fe3O4 confirmed within narrow temperature window during the treatment. Magnetic characterization magnetite thin films temperature, applied magnetic field and orientation were performed. highly stoichiometry- impurity-sensitive Verwey...
The geometry of topological insulators (TIs) has a major impact on the magnetoelectric band structure their surface states. Here, we investigate states cylindrical TI bismuth telluride selenide nanowires with three different diameters, by parallel and transverse magnetoresistance (MR) measurements. In configuration, observe Aharonov-Bohm oscillations as well weak antilocalization, indicating two-dimensional magnetic fields, observed MR that are non-linear against reciprocal field thus cannot...
Bi2Se3 nanoplate devices are synthesized on SiO2 and ferrimagnetic insulator substrates. We experimentally demonstrate that ferromagnetism is induced into the bottom surface. The symmetry broken states give rise to an additional Shubnikov–de Haas frequency leads a decoupling of top quantum Hall effects. present three-channel model separates bulk, surface contributions resistance, indicating presence two shifted half-integer QHEs.
Locally induced, magnetic order on the surface of a topological insulator nanowire could enable room-temperature quantum devices. Here we report realization selective control over states single facet rectangular Bi2Te3 via insulating Fe3O4 substrate. Low-temperature magnetotransport studies provide evidence for local time-reversal symmetry breaking and enhanced gapping interfacial 1D energy spectrum by perpendicular magnetic-field components, leaving remaining facets unaffected. Our results...
Rapid and reproducible assembly of aligned nanostructures on a wafer-scale is crucial, yet one the most challenging tasks in incorporation nanowires into integrated circuits. We present synthesis periodic nanochannel template designed for electrochemical growth perfectly aligned, rectangular over large areas. The can be electrically contacted characterized situ using pre-patterned multi-point measurement platform. During wires remain within thick oxide matrix providing protection against...
Iron nanowires with a square cross section are grown by pulsed electrodeposition within newly developed nanochannel template that allows for easy characterization. Measurements of the magnetoresistance as function magnetic field and temperature performed large parameter window allowing investigation magnonic contribution to electrodeposited iron nanowires. Values dependent magnon stiffness D ( T ) extracted: = 0 (1 – d 1 2 365(1 4.4 × 10 –6 · K –2 meV Å . magnified image (© 2015 WILEY‐VCH...
NbP is a recently realized Weyl semimetal (WSM), hosting points through which conduction and valence bands cross linearly in the bulk exotic Fermi arcs appear. However, most intriguing transport phenomenon of WSM, chiral anomaly-induced negative magnetoresistance (NMR) parallel electric magnetic fields, has yet to be observed NbP. In intrinsic lie far from energy, making magneto-transport elusive. Here, we use Ga-doping relocate energy sufficiently close points, for different surfaces are...
The magnetic stability of a multilayer system formed by N slabs separated nonmagnetic spacers has been studied, emphasizing the role dipolar interactions among slabs. By means numerical and analytical calculations, we have identified regime in which behave independently, i.e., critical thickness spacer at can be safely disregarded. methodology used to establish this distance for other geometries, as it is useful tool identify regimes non-interacting