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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
841

Lort-Sveriges död : Retoriska strategier i Ludvig Nordströms Lort-Sverige

Olander, Elise January 2019 (has links)
No description available.
842

Whistleblowing e direito penal : an?lise de uma pol?tica criminal de combate aos crimes econ?micos fundada em agentes denunciantes

Macedo, Cassio Rocha de 20 March 2018 (has links)
Submitted by PPG Ci?ncias Criminais (ppgccrim@pucrs.br) on 2018-05-09T18:45:14Z No. of bitstreams: 1 Ca?ssio - Dissertac?a?o completa.pdf: 7347040 bytes, checksum: 9fcfee32ac1d6666851aa8feef19f2aa (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2018-05-15T12:26:06Z (GMT) No. of bitstreams: 1 Ca?ssio - Dissertac?a?o completa.pdf: 7347040 bytes, checksum: 9fcfee32ac1d6666851aa8feef19f2aa (MD5) / Made available in DSpace on 2018-05-15T12:32:08Z (GMT). No. of bitstreams: 1 Ca?ssio - Dissertac?a?o completa.pdf: 7347040 bytes, checksum: 9fcfee32ac1d6666851aa8feef19f2aa (MD5) Previous issue date: 2018-03-20 / This thesis is mainly based on the intersection between whistleblowers, disclosure of sensitive information and criminal law. For that matter, the research aims to examine the juridical conception of whistleblowing and is set to understand why whistleblowers around the world are worthy of encouragement and legislative protection at the same time that a lot of them are criminally prosecuted. The fact is that their disclosure of information leads law enforcement authorities to discover illicit acts (of which the whistleblower has knowledge but is not involved). Thus, nowadays several countries around the globe created laws to incentive (legal protection against reprisals) and reward whistleblowers (with a percentage of the monetary sanctions collected by the state if the information delivered by the whistleblower was valuable to a successful legal judicial or administrative action). Unlikely others institutes related to criminal prevention such as plea-bargaining or criminal compliance, the practice of whistleblowing have its own specifications that will be examined in this study. The importance of whistleblowing has resulted in its legislative expansion due to the possibilities of discovering and preventing illegal practices through the disclosure of information by a whistleblower. The focus of my research lies in this figure that arouses so much interest, sometimes seen as heroic or as a traitor. Therefore, the research develops reflecting the possibilities of constructing a criminal policy based on this innovative kind of law. / O presente estudo objetiva examinar o instituto do whistleblowing, desde a sua conceitua??o jur?dico-penal, passando por sua constru??o social enquanto fen?meno, at? sua expans?o internacional enquanto objeto de cria??o legislativa. A figura do whistleblower, um sujeito denunciante, al?m de recente, traz consigo complexidades que a tornam digna de tutela. Tratase de uma figura que, na condi??o de membro (ou ex-membro) de determinada empresa ou organiza??o (seja p?blica ou privada), leva ?s autoridades o conhecimento que det?m sobre atividades il?citas, pr?ticas anti?ticas e toda a sorte de crimes que estavam sendo praticados sob controle dos pr?prios membros de tal organiza??o. Diferentemente de outros institutos, em mat?ria penal, que v?m ? mente quando se menciona den?ncia e dela??o ou, ainda, quando se pensa no aspecto de ado??o de mecanismos preventivos a fim de evitar delitos dentro de institui??es, a pr?tica de whistleblowing consiste em instituto com conceitua??o espec?fica. O atual entendimento, em diversas legisla??es do mundo, ? que a figura do whistleblower ? digna de tutela e, tamb?m, de incentivo, pois demonstrou ser instrumento valioso tanto na preven??o, quanto no descobrimento de condutas delitivas.
843

Ab initio simulations of topological phase transitions in Dirac semimetal Cd3As2 doped with Zn and Mn impurities

Rancati, Andrea January 2019 (has links)
In this work we exploit the unique characteristics of a Dirac semimetal material to be symmetry-protected, to investigate dierent topological phase transitions provided by chemical dopings, focusing in particular on the electronic, magnetic and topological properties of the doped systems, studied by the mean of rst-principles methods based on density functional theory (DFT) approach. In particular these doped systems, besides being of interest for investigating the role of topology in solid state physics, could have a great potential for practical application since the dierent topological phases that come along with the chemical dopings allow one to exploit the unique properties of topological materials. The starting point for our study will be the material called cadmium-arsenide (Cd3As2), an example of a topological Dirac semimetal, which is chemically stable at ambient conditions. Chapter I presents a general introduction to topology, especially in condensed matter physics, and to the main physical properties of the topological materials we mentioned. Then, in chapter II, we briey present the methods and the computational tools that we used for our study. In chapter III a more detailed introduction to our work is given, along with a schemetic view of the path we followed, together with the results that we obtained for pristine Cd3As2, which we use as bench mark for our computational methods. Finally, in chapter IV and V, the results for the doped systems are presented and discussed, respectevely for the non-magnetic (IV) and magnetic (V) dopings. Our study has enabled us to discern how doping can give rise to see dierent topological phase transitions. Specically our work shows that dierent realizations of non-magnetic doping gives rise to dierent topological phases: the topological Weyl semimetal phase, which is of great interest since it can support a robust quantum spin Hall eect, and a very special mixed Dirac + Weyl phase, where surprisingly both a Dirac and a Weyl phase can coexist in the same system. Furthermore, magnetically doped systems show the emergence of a magnetic Weyl phase, which can support a quantum anomalous Hall eect. Our work can be the starting point for future studies, both theoretical and experimental, in which the unique physical properties we found in the doped Cd3As2 systems can be further investigated, in order to exploit them for practical applications.
844

VIOL?NCIA DENUNCIADA CONTRA CRIAN?AS E ADOLESCENTES, NOS CONSELHOS TUTELARES DE FEIRA DE SANTANA - BA, 2003-2004.

Barbara, Josele de Farias Rodrigues Santa 31 July 2006 (has links)
Made available in DSpace on 2015-07-15T13:31:40Z (GMT). No. of bitstreams: 1 Tese Josele F R Sta Barbara.pdf: 616991 bytes, checksum: ad1b5982295673dcdb013f3d7562bfd5 (MD5) Previous issue date: 2006-07-31 / The violence against children and adolescents has been considered an important question of public health, in the different countries and socio-cultural contexts, occupying place of prominence in the directed international politics to the Human Rights. Objective: to characterize the violence against children and adolescents, how much to the aspects related to the victims and aggressors. Materials and Method: One is about a transversal study, with secondary data of the registers of the denunciations of violence against children and adolescents, in the Advice To tutor I and II of the city of Fair of Santana, in the period of 2003 and 2004. The data had been collected through a form, consisting changeable partnerdemographic related the child and vitimizados adolescents, to familiar and the aggressive ones; characterization of the violence forms; e encaminhamentos in the Net of Attendance. Analyses had been carried through descriptive, through the calculation of the absolute and simple frequencies, as well as bivaried analysis, through the association between et?ria band ((1 year; 2-5 years; 6-9 years; 10-13 years; 14-16 years; e 17-19 years complete) and sex of the adolescent child, with other 0 variable related to the forms of violence and characterization of the aggressors. Results: They had totalized 1293 registers of denunciations of violence against children and adolescents, in the Advice To tutor I and II. The place of bigger occurrence of these 27 registers was the domicile with 1011 (78.1%) of the registers. The types of more frequent viol?ncias had been the recklessness, the physical violence and the psychological violence; more frequently in the 2-5 bands years, 6-9 years and 10-13 years, and important ratios in minors of 1 year. The sexual violence presented greater prevalence between adolescents, much even so with registers in all the other bands of age. The different forms of violence had been equivalents between the sexos. The data of etnia and escolaridade of the victims had presented decreases ratio and registers, compromising the analysis. The main source of denunciation was anonymous 398 (30.8%). The mother was the main aggressor, with 646 (47.7%) of the registers of physical, psychological violence and familiar recklessness. The data related to the age and state of conscience of the aggressor did not meet in the registers. Final Considerations: The results of this research had pointed with respect to the necessity of sensitization and formation of the professionals of the Net how much to the register of important 0 variable, on to the ethnic aspects, among others, searching the improvement in the quality of the registers in the Advice To tutor; as well as the necessity of complementary research, with primary data and minute analyses, in view of contributing with the actions of confrontation and spreading of it It dials Denunciation ; important subsidy it to be able public and local institutions, in the elaboration of politics directed to the social development, protection and prevention of the violence, as well as in the qualification of the attendance of the cases for the Net. / A viol?ncia contra crian?as e adolescentes tem sido considerada uma importante quest?o de sa?de p?blica, nos diferentes pa?ses e contextos s?cio-culturais, ocupando lugar de destaque nas pol?ticas internacionais voltadas aos Direitos Humanos. Objetivo: caracterizar a viol?ncia contra crian?as e adolescentes, quanto aos aspectos relacionados ?s v?timas e agressores. Materiais e M?todo: Trata-se de um estudo transversal, com dados secund?rios dos registros das den?ncias de viol?ncia contra crian?as e adolescentes, nos Conselhos Tutelares I e II do munic?pio de Feira de Santana, no per?odo de 2003 e 2004. Os dados foram coletados atrav?s de um formul?rio, constando vari?veis s?cio-demogr?ficas relacionadas ? crian?a e adolescentes vitimizados, aos familiares e agressores; caracteriza??o das formas de viol?ncia; e encaminhamentos na Rede de Atendimento. Foram realizadas an?lises descritiva, atrav?s do c?lculo das freq??ncias absolutas e simples, assim como an?lise bivariada, atrav?s da associa??o entre faixa et?ria (≤ 1 ano; 2-5 anos; 6-9 anos; 10-13 anos; 14-16 anos; e 17-19 anos completo) e sexo da crian?a/ adolescente, com outras vari?veis relacionadas ?s formas de viol?ncia e caracteriza??o dos agressores. Resultados: Totalizaram 1293 registros de den?ncias de viol?ncia contra crian?as e adolescentes, nos Conselhos Tutelares I e II. O local de maior ocorr?ncia desses registros foi o domic?lio com 1011 (78,1%) dos registros. Os tipos de viol?ncias mais freq?entes foram a neglig?ncia, a viol?ncia f?sica e a viol?ncia psicol?gica; com maior freq??ncia nas faixas de 2-5 anos, 6-9 anos e 10-13 anos, e importantes propor??es em menores de 1 ano. A viol?ncia sexual apresentou maior preval?ncia entre adolescentes, muito embora com registros em todas as outras faixas de idade. As diferentes formas de viol?ncia foram equivalentes entre os sexos. Os dados de etnia e escolaridade das v?timas apresentaram baixas propor??es e registros, comprometendo a an?lise. A principal fonte de den?ncia foi an?nima 398 (30,8%). A m?e foi o principal agressor, com 646 (47,7%) dos registros de viol?ncia f?sica, psicol?gica e neglig?ncia familiar. Os dados relacionados ? idade e estado de consci?ncia do agressor n?o se encontravam nos registros. 26 Considera??es Finais: Os resultados desta pesquisa apontaram para a necessidade de sensibiliza??o e forma??o dos profissionais da Rede quanto ao registro de importantes vari?veis, ligadas aos aspectos ?tnicos, entre outras, buscando o aprimoramento na qualidade dos registros nos Conselhos Tutelares; assim como a necessidade de pesquisas complementares, com dados prim?rios e an?lises minuciosas, tendo em vista contribuir com as a??es de enfrentamento e divulga??o do Disque Den?ncia ; importante subs?dio para o poder p?blico e institui??es locais, na elabora??o de pol?ticas voltadas ao desenvolvimento social, prote??o e preven??o da viol?ncia, assim como na qualifica??o do atendimento dos casos pela Red
845

Den kreativa processen : inom evenemangsföretag / The creative process : in the event company

Karlsson, Amanda, Ylitalo, Lisa January 2014 (has links)
Kreativitet har blivit en allt viktigare del i vårt samhälle och vissa forskare går så långt som att säga att vi är på väg in i den kreativa tidsåldern. Företag har uppmärksammat fenomenet mer och mer och det finns många fördelar att vinna genom att arbeta med ett kreativt fokus. Event management har kommit att växa rejält som yrke de senaste tio åren. Trots sin framväxt ses det fortfarande som en ny och ganska outvecklad disciplin men har blivit beskrivet som ett växande yrke. Evenemangsföretag verkar i en bransch med hög konkurrens där kreativitet kan ses som en nödvändighet för att uppnå en konkurrensfördel. Kreativitet har trots detta inte fått någon given plats när eventprojektets faser beskrivs i akademiska studier. Projekt i allmänhet brukar beskrivas med fyra faser: konceptualisering, planering, implementering och avslutning, där kreativiteten är framträdande inom konceptualiseringsfasen. Vi anser att konceptualiseringsfasen borde ha en given roll inom eventprojekt, vilket kommer ligga som utgångspunkt för denna uppsats.Syftet med uppsatsen är att utforska ämnet kreativitet. Huvudfokus ligger på den kreativa processen, hur den går till och vad som påverkar den inom evenemangsföretag. Genom att belysa ämnet hoppas vi kunna bidra till att kreativitet uppmärksammas som en viktig faktor inom evenemangsföretag. Med grund i denna undersökning tar vi fram en modell som ska leda till reflektion för företag om de arbetar aktivt med kreativitet och bidra som en inspirationskälla. För att få en djupare förståelse för hur den kreativa processen verkar i sitt sociala sammanhang inom evenemangsföretag har vi utfört sju semi-strukturerade intervjuer och en deltagande observation. Det övergripande målet med forskningsmetoderna var att få en större kännedom om hur en idé uppstår och vägen till ett färdigt koncept för ett evenemang, med den kreativa processen som en central faktor. Det empiriska materialet har analyserats efter fördjupade teoretiska studier inom området kreativitet.Kreativitet har många olika betydelser, och för att få en helhetsbild har vi undersökt dess innebörd från fyra olika perspektiv: produkt, process, person och påverkan. Den kreativa personen är någon som har en kreativ självinsikt, är modig, mottaglig för inspiration samt har en strukturerad sida med ett öga för detaljer. Den kreativa processen inom evenemangsföretag sker både i grupp och individuellt. De faser vi har identifierat är förberedelse-, idégenererings-, inkubations-, illuminations- och verifikationsfasen. Det har framkommit att det först sker en kreativ förprocess för att få fram ett projektförslag som ska leda till ett avtal innan den kreativa huvudprocessen tar sin start. Denna process utgår från grundidén som är en del av projektförslaget. Den innehåller samma faser som förprocessen men är av mer omfattande karaktär. Den kreativa processen är linjär, men vid behov kan personerna gå tillbaka till en tidigare fas. Dessutom kan faserna ske parallellt med varandra när flera idéer behandlas samtidigt. Processen resulterar i den kreativa produkten, eller den kreativa utkomsten som vi har valt att namnge det, vilket är konceptet för evenemanget. Den kreativa påverkan består av olika faktorer som kan påverka kreativiteten. Dessa faktorer är: organisationskulturen, organisationsstrukturen, organisationsklimatet, arbetsdesignen, uppdragsgivaren, praktiska faktorer samt ledaren och teamet.
846

Fast fashion mot en hållbar framtid- En studie kring konsumenters attityder till hållbart mode / Fast fashion towards a sustainable future- A study regarding consumers attitudes to sustainable fashion

SJÖLIN, KATARINA, STRÖMBERG, JOHANNA January 2011 (has links)
Under de senaste 15 åren har modeindustrin växt och blivit både snabbare och billigare och begreppet fast fashion har etablerats. Fast fashion är en affärsstrategi inom modeindustrin vars mål är att reducera ledtiderna från idé till butik. Strategin syftar till att tillfredsställa kundernas begär av de senaste trenderna på mycket kort tid. Fast fashion branschen kan sägas stå i motsägelse till en hållbar utveckling, då den representerar korta modecykler där kläder tenderar att bli ”slit och släng” varor. Idag går utvecklingen dock mot en ökad medvetenhet i gröna, miljörelaterade frågor vilket har lett till att fler produkter marknadsförs som gröna produkter. En ökad miljömedvetenhet hos konsumenten har skapat ett behov hos företag att kartlägga den gröna konsumenten. Ur ett företag - och marknadsföringsperspektiv är en förståelse för vad den gröna konsumenten eftersöker en förutsättning, då det är ineffektivt att utveckla gröna produkter om inte kunden attraheras av dem.Syftet med uppsatsen är att uppnå en ökad förståelse för modekonsumentens attityder och uppfattningar kring hållbart mode inom fast fashion branschen på den svenska marknaden. Uppsatsen har en kvalitativ utformning och datainsamling har skett genom två fokusgrupper. Den insamlade empirin har analyserats utifrån den teoretiska referensramen. Den behandlar teorier kring konsumentbeteende med inriktning mot fast fashion konsumenten och den gröna konsumenten. Vidare behandlas segmentering med fokus på grön segmentering och slutligen marknadskommunikation med inriktning mot hållbar och grön kommunikation. Resultatet från de undersökta kunderna är tänkta att generera uppslag för fast fashion företag vid utformning och kommunikation av produkter och aktiviteter kopplade till hållbart mode.Vi kan utifrån resultatet från båda fokusgrupperna urskilja en något motsägelsefull hållning till miljömedvetenhet. Det är tveksamt huruvida de undersökta kunderna ser en problematik i klädkonsumtionen kopplat till miljöproblem. Vidare uppvisar de en skepsis gentemot fast fashion företagens hållbara mode då de ifrågasätter trovärdigheten och äktheten. Gällande hur hållbart mode kan kommuniceras kan sägas att intervjupersonerna eftersöker en tydlighet i hur budskapen kommuniceras. En slutsats i uppsatsen är att den höga omsättningen på produkter framkallar ett ”Köp nu”-beteende hos kunden vilket bekräftar fast fashion kunden som till stor del impulsstyrd i sina inköp. Det är inte behovet av att exempelvis köpa en ny jacka som i första hand styr kundens inköp utan snarare att hon köper för köpandets skull. Denna mentalitet hos de undersökta kunderna bekräftar att fast fashion-mode behandlas som ”Slit och släng”-produkter.Två nyckelord som har vuxit fram ur det empiriska materialet är tydligt och konsekvent. Dessa nyckelord måste vara ständigt närvarande för att fast fashion företag ska kunna kommunicera hållbarhet på ett sätt som appellerar till de undersökta kundernas attityder. Sammanfattningsvis kan sägas att om fast fashion företag lyckas kommunicera hållbarhet på ett attraktivt sätt kan vinsterna bli stora. Genom att positionera sig som ett fast fashion företag som erbjuder hållbart mode kan konkurrensfördelar skapas.Over the past 15 years, the fashion industry has grown in size and become both faster and cheaper and the concept of fast fashion has been established. Fast fashion is a business strategy in the fashion industry which is based on reducing lead times from concept to store. The strategy aims to satisfy customer requests of the latest trends in a very short time span. The fast fashion industry is in a way contradicting a sustainable development, as it represents short fashion cycles where clothes tend to be regarded as disposable products. Today however, we are moving towards a greater awareness concerning green, environmental issues which has resulted in more products that are being marketed as green products. This increased environmental awareness among consumers has created a need for companies to identify “the green consumer”. From a business - and marketing perspective, an understanding of what the green consumer is looking for is a pre-condition, since it is inefficient to develop green products unless they are what the customer desires.The purpose of this paper is to obtain a better understanding of the fashion consumer’s attitudes and perceptions on sustainable fashion concerning the fast fashion industry. The thesis has a qualitative design and the data has been collected through two focus groups. The collected empirical data has been analyzed with the theoretical framework in mind. The theoretical framework deals with theories of consumer behavior with emphasis on the fast fashion consumer as well as the green consumer. We also look at market segmentation with emphasis on green segmentation and finally marketing with a focus on sustainable and green communication. The results gathered from the surveyed customers will hopefully generate ideas for fast fashion companies on how to communicate products and activities related to sustainable fashion.Based on the results from the two focus groups we can discern a somewhat contradictory attitude towards environmental awareness in general. Whether the surveyed customers realize that clothing consumption is linked to some environmental problems is rather doubtful. Furthermore, they exhibit skepticism towards the sustainable fashion offered by fast fashion companies as they question the credibility and authenticity. They also express the need of a clearer and more accessible marketing communication concerning sustainable fashion. One conclusion of this paper is that the high turnover of products creates a "Buy Now"-behavior which confirms the fast fashion customer as largely an impulse buyer. It is not the need for say, a new jacket that primarily govern the customer's purchase, but rather that she is buying for buying's sake. This mentality confirms that fast fashion clothing often is treated as disposable products.Two keywords which have emerged from the empirical material are clear and consistent. These keywords should permeate fast fashion companies in their effort to communicate sustainability in a way which appeals to the surveyed customers attitudes. In summary, if fast fashion companies are able to succeed in communicating sustainability in an attractive way, the gains can become significant. By positioning itself as a fast fashion company offering sustainable fashion a competitive advantage is created. / Program: Textilekonomutbildningen
847

Elektroniskt kungörande av författningar : en IT-politisk lösning ur ett användarperspektiv / Promulgation of Statutes on the Internet : an official IT policy solution from an end user’s perspective

Bergqvist, Anders January 2013 (has links)
This essay analyses the arguments of The Swedish Government Official Report 2008:88 which proposes that the Swedish law (SFS) should shift from promulgation in print to elec-tronic promulgation on a Website. I have studied two aspects of the arguments in the text. On the one hand, the Inquiry’s description of how things might become if their proposal becomes effectuated and, on the other hand, how the present situation is described in the text. The theory I have used is called A Garbage Can Model of Organizational Choice, which pictures organizations as often irrational in dealing with problems, solutions and decision making. The chronological order is broken up and a solution to a problem often precedes the problem itself, the latter being so to speak ”picked up from the garbage can” and put on the agenda if proven adequate. The results of my analysis show that the ambition of the Inquiry has been to problematize the traditional way of promulgating the Swedish law in order to make a version on the Webb look more indispensable. Thus arguments in support of the reform have been drawn from the comparison rather than from the virtues of the reform itself.But even now, four years after the report was published, there is no sign of the proposal being taken further in the legislative process. My conclusion is that the committee report certainly proves that the Internet solution is possible but fails to show that it is appropriate. And was there a real problem to begin with? / Program: Bibliotekarie
848

Digitala verktyg som medierande artefakter i förskolan : En studie om hur sex förskollärare beskriver användningen av digitala verktyg i undervisningen / Digital tools as mediating artifacts in Preschool : A study of how six preschool-teachers describe the use of digital tools in early childhood education

Heinonen, Mariam, Celepli, Berivan January 2019 (has links)
This study aims at investigating how preschool teachers view their digital competence and how they describe the use of digital tools in early childhood education. To investigate this, data has been collected using qualitative interviews, which later on have been analyzed with the analysis method Grounded Theory. The theoretical framework of this study has been sociocultural, inspired by the thoughts of Vygotskij. The result of the study shows that preschool teachers emphasize a conscious use of digital tools so that these will become beneficial in teaching. The preschool teachers describe different ways of using digital tools in teaching and view them as resources to mediate learning. The conclusion of the study is that the teacher plays an important role for the outcomes of children’s learning when working with digital tools. Despite the fact that the teachers show positive attitudes towards digital tools in early childhood education, it is required that the teachers know how to use these in order to foster learning. Therefore there is a need to invest in capacity building in ICT among preschool teachers.
849

Den svarta legenden och begreppsanvändningen avurbefolkningen i Amerika i spanskläroböcker : En studie om representationen av upptäckten ochkoloniseringen av Amerika och benämningar påurbefolkningen i Amerika i spanskläroböcker. / The black legend and the notions of native Americans in Spanishtextbooks.

Jensen, Elsa January 2019 (has links)
Att få möjlighet att reflektera kring livsvillkor i länder där det spanska språket talas är ett av syftena för moderna språk både på högstadiet och gymnasiet. Eftersom det spanska språket är det språk som flest elever väljer att studera betyder det också att fler elever möter de spanska läroböckernas innehåll. Syftet med denna studie har varit att undersöka hur läroböcker i spanska inriktade på högstadiet och gymnasiet representerar upptäckten och koloniseringen av Amerika och med vilka begrepp som urbefolkningen i Amerika benämns i dessa böcker. Resultatet av studien visar att den historiska händelsen ges olika utrymme i läroböckerna och att representationen av upptäckten och koloniseringen av Amerika domineras av det historiska perspektivet den svarta legenden. Dessutom förekommer olika begrepp för att benämna urbefolkningen i Amerika och vissa begrepp kan ifrågasättas om de stämmer överens med Läroplanen och dess värdegrund.
850

The interaction of light and magnetism in the TbxCo100-x system

Ciuciulkaite, Agne January 2019 (has links)
Development of the faster and denser magnetic memory storage elements has been an active area of research since early 20th century. The path of research on magnetization manipulation began with firstly changing the magnetization state of a medium in an external magnetic field, then heating of a medium and magnetizing with a permanent magnet was explored, while the latest efforts have been focused on switching the magnetization only by a polarized laser light. Nowadays due to the technological advancement of lasers and material fabrication methods, the search and development process of magnetic memory elements is much faster. The implementation of such technologies, however, relies on finding suitable magnetic materials which would allow for a fast magnetization writing and read-out processes and would remain magnetized, even with the reduced dimensions. Ferrimagnetic rare Earth - transition metal (RE-TM) alloys have been used for fabricating magneto-optical recording media already since the 1990’s. Relatively recently, in 2007, it was demonstrated that the ferrimagnetic GdFeCo alloy magnetization state can be switched using only circularly polarized laser light. Hence, ferrimagnetic RE-TMalloys could be suitable candidates for all-optical light-induced magnetization switching (AOS), without any external magnetic field. Another combination of RE-TM alloys that was shown to exhibit AOS is ferrimagnetic amorphous alloys containing terbium and cobalt (Tb:Co). They have attracted attention due to their strong out-of-plane magnetic anisotropy, high magneto-optical activity and amorphicity, which makes them attractive from a fabrication point of view since a variety of substrates and buffer layers could be used for growing such layers. In this Thesis, TbCo alloys are investigated in order to examine how the magnetic, optical and magneto-optical properties could be tuned by varying the elemental ratio and film thickness. The main question that was addressed here was whether such a system is suitable for fabrication of nanosized magnetic elements as the building blocks for the magnetic memory applications. TbCo alloys were prepared as thin films by magnetron co-sputtering method onto different substrates and buffer layers. Films were characterized using a variety of techniques such as an ion beam analysis, an x-ray reflectivity and diffraction, and magneto-optical characterization techniques. It was observed that the properties of such alloys depend not only on the Tb:Co ratio but also on the film thickness and an underlying buffer layer. Magnetization compensation point, at which the magnetization of a film is zero, as in an antiferromagnet, can be modified depending on the buffer layer. All-optical switching (AOS) of magnetization experiments were performed on the fabricated samples. It was determined that AOS with at least 50-100 laserpulses can be achieved for the films grown directly onto fused silica substrates and with the compositions above the magnetization compensation point at room temperature, in the range of 24 - 30 at.% Tb. In the Outlook, the initial efforts of patterning the films into the arrays of nanosized elements are presented. It is demonstrated that after the lithographic patterning of the films, the resulting nanosized elements remained out-of-plane magnetized. In this work it is shown that the ferrimagnetic TbCo alloy system is a potential candidate material for bothfacilitating AOS and the fabrication of arrays of nanomagnets. Combining the TbCo alloys,which show AOS, together with a suitable buffer layer and patterning the hybrid structure,could enable selective element-by-element magnetization switching for the magnetic memorystorage devices.

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