Bio: W. Wiebauer is an academic researcher from University of Erlangen-Nuremberg. The author has contributed to research in topics: Hall effect & Scattering. The author has an hindex of 1, co-authored 1 publications receiving 47 citations.
TL;DR: In this paper, the dependence of the resistivity and the Hall effect of copper films on the method of film preparation and the film thickness has been studied before and after adsorption of carbon monoxide.
TL;DR: In this paper, the effect of the adsorption on the resistance of thin film electrodes, including adsorptions processes of ions, organic compounds, oxygen, hydrogen and underpotential deposition, is discussed.
01 Jan 1975
TL;DR: In this article, the effects of specific adsorption on the in situ resistance measurement were studied using polycrystalline gold film electrodes of various thicknesses, and a differential technique was developed where the instantaneous changes in the electrode resistance are correlated to the voltammetric current in linear sweep voltammetry.
TL;DR: In this paper, the authors measured the resistivity and the thermoelectric power of palladium films as functions of the thickness, the annealing temperature and the measuring temperature.
10 Oct 2013
TL;DR: In this paper, the magnetic microstructure of domain walls located at the bend of soft magnetic V-shaped nanowires were observed by means of scanning electron microscopy with polarization analysis (SEMPA).
Abstract: This thesis deals with three topics in the field of research of magnetogalvanic effects in ferromagnets of reduced dimensions. The first subject concerns the magnetic microstructure of domain walls located at the bend of soft magnetic V-shaped nanowires. Three different types of domain walls were observed by means of scanning electron microscopy with polarization analysis (SEMPA) and obtained from micromagnetic simulations, namely, the symmetric and asymmetric transverse domain wall as well as the vortex domain wall, that are well known from a straight wire geometry. The implementation of a symmetry breaking bend affects the spatial potential landscape while the details of the pinning behavior of the domain walls at the bend derive from the topology of their microstructures. The dependence of the preponderant domain wall type on bending angle reveals that, besides the wire’s dimensions, the bending angle is a further parameter to adjust the wall type on purpose. Concerning vortex domain walls it is shown that the sense of magnetization rotation around the vortex core, which was found to be inherently linked to the position of the core with respect to the wire’s bisection, is tunable via magnetic seeding fields that are slightly tilted out of the symmetry axis of the wire. The possibility to intentionally control the vortex wall properties gives a high flexibility for future concepts of vortex-based memory devices. The second project of this thesis introduces a method that enables the investigation of the magnetization reversal of individual nanomagnets with lateral dimensions of & 100 nm by means of magnetotransport. The method consists of the preparation of micro-circuits including the creation of the nanomagnet from a laterally homogeneous metallic stack by means of focused ion beam (FIB) technique and allows the subsequent in situ magnetoresistance (MR) investigation utilizing a micromanipulator under ultra-high vacuum conditions. The top-down creation of the nanomagnet is based on rendering the surrounding metal paramagnetically by means of ion beaminduced mixing of the material layers of the stack. Importantly, as the paramagnetic material constitutes the input leads it has to maintain a good electrical conductance to guarantee a high sensitivity for the magnetogalvanic effects of the nanomagnet. In order to find adequate stacks an in situ MR method for characterizing the influence of ion-bombardment on the electrical and magnetic properties was developed. This method was applied for different stacks containing a 20 nm thick soft magnetic permalloy layer. The best suited stack was used to demonstrate the potential and sensitivity of the MR investigations of individual nanomagnets in the case of rectangular prisms (rectangles) with lateral dimensions of 600× 300 nm, 800× 400 nm, and 1000×500 nm. The remagnetization behavior of the two generic cases with the magnetic field applied perpendicularly (hard axis) and in parallel (easy axis) to the long axis of the rectangles obtained from single field cycles is analyzed by utilizing the anisotropic MR (AMR). Reversible and irreversible remagnetization processes are quantified and unambiguously assigned to the involved micromagnetic states. The main result is that the energy density of the micromagnetic Landau state can be obtained from the hard axis remagnetization behavior, in accordance with domain theoretical considerations and micromagnetic simulations. The third subject of this thesis deals with comprehensive investigations of the MR of