Remagnetization and magnetization dynamics in complex magnetic textures, from antidots lattice to nanodots

Wydział FizykiLokalne zaburzenie uporządkowania magnetycznego, które może rozprzestrzeniać się w postaci fali w materiale magnetycznym, zostało przewidziane przez Blocha w 1929 roku i nazwane falą spinową. Periodycznie strukturyzowane układy magnoniczne są sztucznymi ośrodkami o okresowo modulowanych właściwościach magnetycznych, zwane kryształami magnonicznymi. W takich strukturach można znaleźć skomplikowane tekstury magnetyczne takie jak domeny magnetyczne, worteksy czy skyrmiony. Skyrmion jest kwazicząsteczką, charakteryzującą się tzw. ładunkiem topologicznym, będącą możliwie najmniejszym i jednocześnie stabilnym zakłóceniem jednorodnego namagnesowania. W ramach pracy doktorskiej autor zaprezentował pięć publikacji naukowych zawierających wyniki badań: procesów przemagnesowania, rezonansu ferromagnetycznego, propagacji fal spinowych w strukturalizowanych materiałach ferromagnetycznych; stabilizacji skyrmionów w nanokropkach magnetycznych w których możliwe jest istnienie dwóch stanów skyrmionowych (skyrmionu o małej i dużej średnicy) o zbliżonych poziomach energetycznych; badania możliwości formowania skyrmionów w sieci kwadratowej dziur w trakcie procesu przemagnesowania; badania sieci dziur w wielowarstwach ferromagnetycznych z prostopadłą anizotropią, w których zaobserwowano skomplikowaną teksturę magnetyczną. W ostatnim rozdziale doktoratu autor zaprezentował podsumowanie, plany badawcze oraz krótkie zestawienie innych osiągnięć naukowych.Bloch predicted a disturbance in the local magnetic order which can propagate in a magnetic material in a form of wave in 1929. It named as a spin wave since it is related to a collective excitation of the spins in ferromagnetic media. Magnonic crystals are artificial magnetic media with periodically modulated magnetic properties in space, well known as a structure where spin waves band structure consists of intervals of allowed bands of spin-wave frequencies and forbidden band gaps, making them structures with interesting properties. Magnetic skyrmions are solitonic magnetisation textures, whose stability is protected by their topology. In this thesis, the author presents the results of studying the static and dynamic properties of the complex ferromagnetic structures and unique skyrmion properties. The author studied magnetisation textures in patterned thin films during the remagnetisation process. In the next step, he studied the ferromagnetic resonance and characteristic of propagating spin-waves in the same structures. Then, he started investigations of skyrmion stabilisation in nanodisc and skyrmion nucleation process in antidot lattice during the remagnetisation process. Finally, he analysed the complex magnetic textures in patterned multilayers with perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction.Various parts of the presented thesis were supported by the Polish National Science Centre (NCN), Ministry of Science and Higher Education (MNiSW), and European Union Horizon 2020 and other: 1. NCN PRELUDIUM 14, Grant No. 2018/31/N/ST7/03918 (PI), 2. NCN SONATA BIS 2 (2013-2018), Grant No. 2012/07/ST3/00538. 3. EU Horizon 2020 project MagIC Grant No. 644348, 4. Scholarship founded by Adam Mickiewicz University Foundation, 5. Scholarship founded by dr Jan Kulczyk Foundation, 6. OPUS11 (2017-2019), Grant No. 2016/21/B/ST3/00452, 7. OPUS9 (2016-2019), Grant No. 2015/17/B/ST3/00118, 8. "Premia na Horyzoncie" - MNiSW Grant No. 328712/PnH/2016, 9. National Scholarship Program of the Slovak Republic funded by the Ministry of Education, Science, Research, and Sport of the Slovak Republic (two scholarships in 2016/2017 and 2017/2018), 10. The simulations were partially performed at the Poznan Supercomputing and Networking Center (Grant No. 398)

Transitivity of implicative aBE algebras

We prove that every implicative aBE algebra satisfies the transitivity property. This means that every implicative aBE algebra is a Tarski algebra, and thus is also a commutative BCK algebra

On Traczyk's BCK-sequences

BCK-sequences and n-commutative BCK-algebras were introduced by T. Traczyk, together with two related problems. The first one, whether BCK-sequences are always prolongable. The second one, if the class of all n-commutative BCK-algebras is characterised by one identity. W. A. Dudek proved that the answer to the former question is positive in some special cases, e.g. when BCK-algebra is linearly ordered. T. Traczyk showed that the answer to the latter is affirmative for n = 1, 2. Nonetheless, by providing counterexamples, we proved that the answers to both those open problems are negative

FACTORS CONDUCIVE TO INCLUSIVE EDUCATION IN POLISH PRIMARY SCHOOLS IN THE OPINION OF PARENTS

The importance of inclusive education for the education system and more effective social inclusion of students with special educational needs (SEN) and care for its quality in schools is an issue raised both in Europe and more widely at international level. In 2017, a modification of legal provisions in the field of providing psychological and pedagogical assistance to pupils with special educational needs in Poland was introduced. A year later, the Children’s Ombudsman conducted a diagnostic survey, which aimed at getting to know parents’ opinions about the state of inclusive education and the support offered to pupils with SEN in mainstream schools. The obtained data suggest that in the opinion of parents76 schools participating in the study, situation of SEN students can be assessed as satisfactory. Nearly 80% of children attend schools in the vicinity of their place of residence. The teachers and specialists employed in schools are rather well prepared to work with pupils with SEN, they often implement recommendations contained in the opinions issued by psychological and pedagogical counseling centers

BARRIERS IN POLISH INCLUSIVE EDUCATION IN THE OPINION OF STUDENTS' PARENTS WITH SPECIAL EDUCATIONAL NEEDS

The principles of inclusive education have been orientating the ways of working with children and young people with special educational needs for many years. Nevertheless, it is difficult to change the process of modifying the teachers’ thinking about a student with disabilities or deficits in the aspect of teaching him in a state school. In 2017, legal acts in Poland were modified to provide psychological and pedagogical assistance to pupils with special educational needs. However, the Ombudsman for Children received many letters from parents of students who gave examples of violations of their rights at school. Therefore, in 2018 a survey was conducted among parents on the difficulties encountered by their children while studying at school. The research results revealed some irregularities both in the aspect of teaching methods which were applied to children and the cooperation of teachers with parents and other specialists. On this basis, it was possible to identify barriers to inclusive education in Polish schools

Empathy among the members of isolated culture

This article presents a look at the resocialization, as a cultural offer, which were presented for imprisoned persons. Perceiving the phenomenon of the prison subculture, as a threat to the future readaptation, a program with using elements of drama was suggested and presented whether and what scope he can contribute to the increase in the level of empathy in

Spin Dynamics in Patterned Magnetic Multilayers with Perpendicular Magnetic Anisotropy

The magnetization dynamics in nanostructures has been extensively studied in the last decades, and nanomagnetism has evolved significantly over that time, discovering new effects, developing numerous applications, and identifying promising new directions. This includes magnonics, an emerging research field oriented on the study of spin-wave dynamics and their applications. In this context, thin ferromagnetic films with perpendicular magnetic anisotropy (PMA) offer interesting opportunities to study spin waves, in particular, due to out-of-plane magnetization in remanence or at relatively weak external magnetic fields. This is the only magnetization configuration offering isotropic in-plane spin-wave propagation within the sample plane, the forward volume magnetostatic spin-wave geometry. The isotropic dispersion relation is highly important in designing signal-processing devices, offering superior prospects for direct replicating various concepts from photonics into magnonics. Analogous to photonic or phononic crystals, which are the building blocks of optoelectronics and phononics, magnonic crystals are considered as key components in magnonics applications. Arrays of nanodots and structured ferromagnetic thin films with a periodic array of holes, popularly known as antidot lattices based on PMA multilayers have been recently studied. Novel magnonic properties related to propagating spin-wave modes, exploitation of the band gaps, and confined modes, were demonstrated. Also, the existence of nontrivial magnonic band topologies has been shown. Moreover, the combination of PMA and Dzyaloshinskii-Moriya interaction leads to the formation of chiral magnetization states, including N\'eel domain walls, skyrmions, and skyrmionium states