NEKULA, Z. Vývoj Kerrova mikroskopu s časovým rozlišením [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2021.

Posudek vedoucího

Wojewoda, Ondřej

The bachelor thesis of Zdenek Nekula is dealing with the construction of a scanning-time-resolved magneto-optical microscope. In the first part author performed comprehensive literature research on the electromagnetic waves and the Kerr effect. The third chapter is dealing with the used optics and signal processing. The following chapter discusses the mechanical design of the developed microscope. In the last two chapters, the obtained results are presented for both static and dynamic measurements. The student showed diligence and independence in the construction and aligning of the optical setup. The achieved results are of outstanding quality and comparable with the state-of-the-art setups around the world. Unfortunately, the quality of the text and scientific accuracy does not perfectly match the experimental part's standard. Nevertheless, the author constructed and aligned the scanning magneto-optical microscope capable of spatially- and time-resolved quantitative magnetometry. All of the objectives were accomplished, and therefore I recommend the work for defense with an overall grade of A.

Posudek oponenta

Arregi Uribeetxebarria, Jon Ander

The bachelor thesis of Zdeněk Nekula deals with the development of a magneto-optical Kerr effect microscope to characterize dynamic magnetization processes at the microscale. The thesis firstly describes the fundamentals of electromagnetic waves and magneto-optical Kerr effects in detail. Concerning experimental work, Mr. Nekula built a more advanced version of the scanning Kerr effect microscope. A new signal acquisition scheme is based on a smart strategy consisting of four-quadrant based detection, and the possibility to rotate the sample in a magnetic field is added. A user-friendly control and acquisition software is also incorporated. It is satisfactorily shown that scanning Kerr magnetometry is achieved with 500 nm spatial resolution. In addition, the time-resolved capability using a picosecond laser and a pump-probe setting (microwave pump, optical probe) is successfully implemented, a work showing a high command of advanced electronics and data acquisition. The measurements of vortex gyration dynamics in permalloy microdiscs are impressive and of remarkable quality. I would like to give a very positive overall evaluation of the thesis. A very large amount of work has been done and all thesis objectives are accomplished by far. The thesis has a nice graphical layout and the text is generally clear. As a suggestion for improvement, I would point to occasional imprecisions in the text that make appear some concepts confusing. The language style is at times casual, and the organization could be slightly improved (for example, section 2.3 before 2.2). I would also recommend improving the style of references in future work. Despite these minor inaccuracies, I believe that the work is of exceptionally high quality and hence I would like to grant the highest overall mark “A”.

eVSKP id 132932