Techn. University, Diss., 2003--Darmstadt.

In dieser Arbeit werden magnetische Vortex-Dreifachlagen-Systeme untersucht. Mittels Magnetfeld, Strom und Röntgenzirkulardichroismus kann erstmals die magnetische Konfiguration der Vortexlagen mit dem simultan gemessenen Magnetowiderstand verglichen werden. Die senkrecht mit Strom durchflossenen Kobalt-Kupfer-Permalloy Scheiben werden in einem Mehrschrittprozess mittels Elektronenstrahllithographie auf einer Membran hergestellt, um mit Rastertransmissions-Röntgenmikroskopie untersuchbar zu sein. Die Auswertung der STXM-Bilder zeigt das gleiche Verhalten wie die Widerstandsmessungen und erlaubt eine eindeutige Zuordnung. Um auch die kleinsten scheibenförmigen Dreifachlagensysteme mittels ferromagnetischer Resonanz zu messen, wurde die Mikroresonator FMR optimiert. Damit können bereits etwa 2.3*10^7 Kobaltatome gemessen werden, wobei die Empfindlichkeit bis zu 4*10^6 Atomen ausreichend sein sollte. Durch 6-fache Mittelung lässt sich ein Kobaltwürfel mit einer Kantenlänge von 12,5nm detektieren. Dabei sind nicht nur die uniforme Mode, sondern auch lokal angeregte Moden sichtbar. Mittels mikromagnetischer Simulationen lassen sich den Resonanzen Modenbilder zuordnen. Die scheibenförmige Dreifachlage wird mit den FMR-Messungen sowohl mit verringertem Durchmesser, als auch mit reduzierter Zwischenschicht untersucht.

Title: Electricity and magnetism: Hands-on minds-on approach Author: Věra Koudelková Department: Department of Physics Education Supervisor: Doc. RNDr. Leoš Dvořák, CSc., KDF Abstract: The PhD. thesis is focused on high school students' understanding of electricity and magnetism and on experiments which can help students to develop this understanding. The thesis can be divided into two parts: In the first research part typical misconceptions of high school students in the area of electricity and magnetism are described, both misconceptions known from foreign literature and results of Czech Conceptual Test of Electricity and Magnetism. This test is based on the known Conceptual Survey of Electricity and Magnetism, but unlike it and other conceptual tests in electricity and magnetism this new Czech test is intended for high school students. The second part of the thesis is developmental. It contains methodical materials, lab works and experiments which partly arise from the discovered misconceptions. In this part of the work four learning sequences (we chose topics, which were identified as problematic for students), four laboratory works and 13 experiments are described. Prepared materials were verified during instructions in high school and during conferences for physics teachers. Experiences with them are...

The diploma thesis Didactic games and their inclusion in physics education deals with its play in physics teaching at the second grade of primary school. It focuses primarily on electricity and magnetism and is complemented with the possibility of extracurricular activity and formation of positive attitude towards this area of physics and physics as a whole. The work is divided into a theoretical part, which engages in the theory of games, game didactic requirements and methods of its inclusion in the lesson. Furthermore, the motivation and the end of the theoretical part consists of an analysis of electricity as a topic and magnetism in terms of RVP and school educational programs, including cross-cutting themes and key competencies. The second part deals with the various types of games. A general view includes games with physical principles that can be purchased in our market, computer games and options of educaching. The main part of the educational games contains rules and recommended way of games´ categorization. Plays are divided into chapters. According to their use. Games for one pupil , games and activities for the division of students into groups, games for creative thinking and development of communication, games in the role - " role playing ", games for remember, knowledge games, motion games, card games, relaxing games motivated by electric current, games with a physical base. The conclusion is included verification of using games in the classroom, which is based on observation, pupil´s questionnaire and test of students' knowledge in the chosen field.

This master thesis focuses on literature research of problematics linked to power actuators working on electromagnetic principle to accelerate metal projectiles. It’s goal is mathematical analysis and constuction of selected type of electromagntic power actuator – induction coilgun

This master thesis focuses on literature research of problematics linked to power actuators working on electromagnetic principle to accelerate metal projectiles. It’s goal is mathematical analysis and constuction of selected type of electromagntic power actuator – induction coilgun

In the thesis at hand, different concepts of magnetic recording were investigated both from an experimental and theoretical point of view. On the one hand, micromagnetic simulations of bit patterned media were performed examining the influence of magnetic and geometrical parameters on the magnetization reversal mechanism of the bit array. In this regard, the recording concept called exchange coupled composite (ECC) media was applied in combination with bit patterned media (BPM). It was demonstrated that ECC/BPM is superior in terms of narrowing the SFD which is vital for the implementation of BPM as a recording scheme in magnetic data storage deviced. Moreover, the stability of the magnetic state was calculated for single nanomagnets using the nudged elastic band algorithm. It was found out that the magnetic and geometrical properties have a severe influence on both, the energy barrier for magnetization reversal and the magnetization reversal process of the single nanomagnets. On the other hand, experimental studies of granular CoCrPt:SiO2 films deposited on self-assembled arrays of SiO2 nanoparticles with a size from 10 nm to 330 nm have been carried out, showing a distinct size-dependence of the coercive field and remanent magnetization with changing nanoparticle size. Moreover, these films have been irradiated with Co+ ions with different fluences, resulting in a change of the magnetic properties of the films due to both a change of the intergranular exchange coupling of the film and a degredation of the magnetic layers at higher irradiation fluences.

Title: Magnetic excitations in cerium compounds Author: Kristina Vlášková Department: Department of Condensed Matter Physic Supervisor: doc. Mgr Pavel Javorský, Dr., Department of Condensed Matter Physics Abstract: Thanks to presence of only one electron in 4f shell of cerium ion, Ce based compounds reveal wide range of exceptional magnetic properties like valence fluctuations, magnetic ordering or spin glass behavior. In present thesis we mainly focus on tetragonal CeCuxAl4-x system and its magnetic behavior. Former results of inelastic neutron experiments opened discussion about energy levels of cerium ions in CeCuAl3. Except two crystal field excitations also one additional energy level was present, phenomenon of vibron quasi-bound state was proposed to explain observed energy structure. Measurement and analysis of specific heat and neutron inelastic scattering on compounds with various Cu content should help to understand phenomenon of vibron state and also its development with Cu/Al concentration. Another two types of cerium compounds will be investigated in means of specific heat and resistivity measurement, polycrystalline sample of CePt4Al and single crystal of Ce3Ru4Al12. Preparation, characterization and measurement of low temperature properties are subjects of this work. Results will be discussed...

of doctoral thesis Theory of spin-dependent transport in magnetic solids David Wagenknecht Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University 2019 Theoretical and ab initio description of realistic material behavior is complicated and combinations of various scattering mechanisms or temperature effects are often neglected, although experimental samples contain impurities and modern electronics work at finite temperatures. In order to remove these knowledge gaps, the alloy analogy model is worked out in this thesis and implemented within the fully relativistic tight- binding linear-muffin-tin orbital method with the coherent potential approximation. This first-principles framework is shown to be robust and computationally efficient and, consequently, employed to investigate bulk solids and their spintronic applications. Unified effect of phonons, magnons, and alloying gives agreement with literature for temperature-dependent electrical transport (longitudinal and anomalous Hall resistivities) and scattering mechanisms are explained from electronic structures. Moreover, novel data help to identify defects in real samples and experimentally hardly accessible quantities are presented, such as spin polarization of electrical current. Calculated results for both zero...

This thesis focuses on the study of magnetic properties of three 5f electron itinerant ferromagnets UCo0.990Ru0.010Al, UCoGa and URhGa and investigation of their phase diagrams. The single crystals of high-quality were prepared by Czochralski method for all three compounds. The physical properties at ambient pressure were studied by macroscopic methods (magnetization, electrical transport and heat capacity measurements) and also by magnetic force microscopy (MFM). The measurements were done under various external conditions (high pressure, low temperatures, high magnetic field). Through all these measurements and external conditions we investigated the interesting physical properties and the ferromagnetic phase diagrams. Effect of different conditions during the preparation and the thermal treatment on UCoGa was studied on two different single crystals. We show that annealing leads to improved quality of samples and the gallium evaporation from the melt during the growth leads to lower quality in parts of the ingot closer to melt. MFM images of UCoGa below the ordering temperature show domain branching and narrow magnetic domains wall made only of neighboring atoms with opposing moments. We have grown first ever single crystal of URhGa with ferromagnetic ordering temperature TC = 41 K. Anomalous maximum in...