VELIČ, A. Laser control of the metamagnetic phase transition in FeRh nanostructrures [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2024.

Posudek vedoucího

Arregi Uribeetxebarria, Jon Ander

The diploma thesis of Mr. Velič deals with a novel and interesting strategy to control the magnetic phase in metallic FeRh nanostructures via laser pulses. The thesis summarizes the results of a very large amount of work, comprising sample fabrication via lithography, magnetic force microscopy measurements, preparing a laser optical setup, and the actual demonstration of light-induced control of the phase transition. The progress concerning the measurements based on laser control was only realized towards the end of working period, as sample fabrication optimization resulted to be more complex than anticipated. These difficulties prevented a more thorough exploration of the dependence on experimental parameters and answering more fundamental questions. However, I want to remark that the thesis gathers in the end very solid experimental work, providing ideas and results with high scientific interest. Mr. Velič was determined and persistent, worked very hard and steadily, particularly in the second semester, and showed resources for problem solving. The manuscript is generally well written and contains the necessary materials for making it a comprehensive text. Even if some aspects could have been improved (e.g., a more precise introduction to phase transitions, or a slight improvement in the use of language), I think the work is excellent, therefore I would like to propose the highest mark, A.

Posudek oponenta

Dubroka, Adam

Subject: Review of master's thesis of Bc. A. Velič, "LASER CONTROL OF THE METAMAGNETIC PHASE TRANSITION IN FERH NANOSTRUCTURES " The master thesis of Bc. A. Velič is devoted to exploring bi-directional changes between the antiferromagnetic and ferromagnetic phases of FeRh mesostructured disks induced by light pulses. The thesis starts with chapters devoted to an introduction to magnetism in general and magnetic phase transitions in FeRh in particular. Used experimental methods such as thin film deposition, lithography, vibrating sample magnetometry, and magnetic force microscopy are well introduced. The results of the thesis are summarized in chapters 4-6. Chapter four describes in detail the deposition of FeRh films by magnetron sputtering and the consecutive microstructuring using lithography, which was particularly demanding. The thesis presents in detail two different lithography processes whose goal was to obtain mesoscopic disks of FeRh that exhibit the supercooling effect of the ferromagnetic phase. This goal was achieved as demonstrated by magnetic force microscopy presented in chapter five. Chapter six focuses on the final step in the original idea, that is, to show that both the antiferromagnetic-to-ferromagnetic transition and the ferromagnetic-to-antiferromagnetic transition could be induced by laser pulses, which was successfully achieved. In summary, the presented thesis demonstrates the student's capabilities of elaborating complex and demanding technological and scientific tasks. The thesis is well-structured and written in clear English. The text has a certain number of typos that, however, do not diminish its overall readability. The whole text is well-referenced with sources from the literature. I very much enjoy the overall spirit of the thesis, which reflects the author's large enthusiasm and extensive efforts devoted to the subject. Undoubtedly, I recommend the thesis to be accepted as a successful thesis.   In Brno, 4th June, 2024                                 doc. Mgr. Adam Dubroka, Ph.D.

eVSKP id 158021