Strukturne, morfološke in kemijske lastnosti stičnih ploskev med kovino in topološkim izolatorjem

Topological insulators (TIs) represent a new state of matter that possess a different band structure than regular insulators or conductors. They are characterized with a band gap in the bulk and conductive topological states on the surface, which are spin polarized and robust toward contamination or deformation of the surface. Since the intriguing properties of the TIs are localized at the surface, it is important to obtain knowledge of the possible phenomena happening at the interface between TIs and other materials. This is especially true in the case of metals, due to the fact that such interfaces will be present in the majority of foreseen TI applications. The presented study combines microscopy and spectroscopy techniques for characterization of morphology, stability and chemical interaction at the interface between TI and metals deposited by means of physical vapor deposition. Our research is based on the interface of Bi2Se3 topological insulator with Ag, Ti and Pt – metals that can be encountered in devices or applications predicted to utilize the special properties of topological insulators. STM and SEM imaging of Ag/Bi2Se3 interface showed that Ag atoms arrange on the surface in the form of islands, whereas significantly bigger agglomerates are found at the surface steps. The interface was found to be unstable in time and resulted in the absorption of the metal into the crystal at room temperature. Evidences of a chemical reaction at the Ag/Bi2Se3 interface are presented, showing that new phases (Ag2Se, AgBiSe2 and metallic Bi) are formed. Deposition of Ti on Bi2Se3 resulted in different morphologies depending on the film thickness. At a very low coverage (<1 Å) islands are formed. However, the islands growth is hindered before the completion of a full layer due to the occurrence of a chemical reaction. No surface features could be detected by SEM for Ti coverage up to 20 nm. In contrary, when Ti thickness reached 40 nm, compressive stress triggered buckling of the deposited film. XPS analysis revealed that a redox solid-state reaction occurs at the Ti/Bi2Se3 interface at room temperature forming titanium selenides and metallic Bi. The reaction has significant kinetics even at cryogenic temperature of 130 K. Pt forms a homogenous film over the whole substrate surface, which is stable in time at room temperature. Although the interface of Pt with Bi2Se3 was found to be i less reactive compared to Ag and Ti, an interfacial phase formed upon annealing to ∼90 °C was detected by TEM cross section experiment. A model for prediction of interfacial reactions between a metal and Bi2Se3 based on the standard reduction potential of the metals and Gibbs free energy for a model reaction is presented. Based on these two values the reaction can be expected to result in the formation of binary and/or ternary selenides and Bi. Presented work shows on the importance of metal/topological insulator interfaces characterization taking into account the possibility of a chemical reaction with all of its consequences. Results should be considered for future theoretical and applicative studies involving such interfaces as well as for the possible engineering of 2D TI heterostructures.V doktorski disertaciji je predstavljena študija stičnih ploskev med kovino in topološkim izolatorjem (TI). Topološki izolatorji predstavljajo novo vrsto materialov, ki se po svoji elektronsko pasovno strukturi razlikujejo od običajnih izolatorjev ali prevodnikov. Za notranjost materiala je značilen prepovedan pas, medtem ko so na površini prisotna prevodna topološka stanja. Stanja na površini so topološko zaščitena in posledično veliko bolj obstojna v primeru kontaminacije ali deformacije v primerjavi z običajnimi elektronskimi stanji na površini. Poleg tega so topološka stanja na površini spinsko polarizirana, kar preprečuje povratno sipanje elektronov pri transportu. Ker so posebne lastnosti TI lokalizirane na površini, so študije stičnih ploskev med TI in drugimi materiali izrednega pomena. To še posebej velja za primer stične ploskve s kovino, saj je takšen kontakt predviden za večino aplikacij, kjer bi se TI lahko uporabljali. Raziskava zdužuje mikroskopske in spektroskopske metode za karakterizacijo morfologije, stabilnosti in kemijskih interakcij na stični površini med TI in kovinami, ki so nanešene s pomočjo metod fizikalnega nanosa iz parne faze. Raziskava opisuje stično ploskev med topološkim izolatorjem Bi2Se3 ter Ag, Ti in Pt – kovinami, ki jih srečamo v napravah ali drugih aplikacijah, predvidenih za izkoriščanje posebnih lastnosti topoloških izolatorjev. STM in SEM meritve stične ploskve Ag/Bi2Se3 so pokazale, da atomi Ag na ravni površini Bi2Se3 tvorijo skupke, medtem ko se na prehodih med posameznimi plastmi tvorijo veliko večji aglomerati. Stik med Ag in Bi2Se3 se je izkazal kot nestabilen, saj sčasoma pride do absorpcije kovine v substrat. Posledično se morfologija površine spremeni. Zaznane spremembe so posledica kemijske reakcije na stični ploskvi. Uporaba različnih spektroskopskih metod je omogočila določitev produktov, ki nastanejo v reakciji, in sicer Ag2Se, AgBiSe2 in Bi. Morfološka struktura Ti na Bi2Se3 je odvisna od debeline nanešenega filma. Pri nanosu zelo majhne količine Ti (5 nm) je pokazala enako morfologijo površine kot v primeru čistega Bi2Se3. Pri večjih debelinah nanešenega Ti (okrog 40 nm) pa se je v filmu ustvarila tlačna napetost, ki je sprožila nagubanje in mehanski razpad filma. XPS iii analiza je pokazala, da pride na stiku Ti/Bi2Se3 do kemijske redoks reakcije v trdnem, pri kateri se tvorijo titanovi selenidi in kovinski Bi. Reakcija poteče hitro tudi pri nizki temperaturi (130 K). Pt tvori homogen film čez celotno površino Bi2Se3. Film ne kaže vidnih morfoloških sprememb v času po hranjenju pri sobnih pogojih. Čeprav se je stična ploskev med Pt in Bi2Se3 izkazala za veliko manj reaktivno v primerjavi z Ag in Ti, je segrevanje vzorca na temperaturo ∼90 °C privedlo do nastanka nove faze, ki je bila detektirana s pomočjo TEM. Na osnovi standardnega redukcijskega potenciala in Gibbsove proste energije za teoretično reakcijo smo izdelali model za napovedovanje reakcije na stični ploskvi med kovino in Bi2Se3. Glede na omenjeni vrednosti lahko predvidimo ali bo kemijska reakcija privedla do nastanka binarnih in/ali ternarnih selenidov in Bi. Predstavljeno delo kaže na pomen karakterizacije stičnih ploskev kovina/topološki izolator z ozirom na nastanek kemijske reakcije in posledic, ki jih le- ta povzroči. Dobljene rezultate je smiselno upoštevati za nadaljne teoretične in eksperimentalne študije, ki vključujejo podobne stične površine, kot tudi za možnost načrtovanja in sintezo 2D heterostruktur s topološkimi izolatorji

STUDENTS AS POLICY ACTORS: THE TDSB EQUITY FOUNDATION STATEMENT AND COMMITMENTS TO EQUITY POLICY

Discrimination on the basis of homophobia/transphobia in many schools is an internationally recognised problem. The Toronto District School Board’s (TDSB) Equity Foundation Statement and Commitments to Equity Policy (EFS) provides an explicit mandate to schools in its jurisdiction to address such discrimination and educate about sexual and gendered diversity. This research, which draws on the work of Ball et al. (2012), examines how lesbian, gay, bisexual, transgender, and queer (LGBTQ) equity work was being implemented in two TDSB high schools. In particular, it illustrates how some students were more than subjectively produced by policy, but were agentic policy actors who were integral to the enactments of LGBTQ equity work undertaken in the schools

Gender and Sexuality Diversity in a Culture of Limitation

Gender and Sexuality Diversity in a Culture of Limitation provides an outstanding and insightful critique of the ways that contemporary education is impacted by a range of political, social and cultural influences that inform the approaches that schools take in relation to gender and sexuality diversity. By applying feminist poststructural and Foucauldian frameworks, the book examines the ongoing impact of broader socio-cultural discourse on the lives of gender and sexuality diverse students and teachers. Beginning with an overview of the impact of how a culture of limitation is realised in Australia, the focus moves beyond this context to examine state and federal policies from comparable societies in countries including the USA and the UK and their effect on the production of knowledges and what’s permissible to include in educational curriculum. This research-driven book thus provides a comparative, international overview of the current state of gender and sexuality diversity in schools, and convincingly demonstrates that despite some empowerment of gender and sexuality diverse individuals, silencing and marginalization remain powerful forces. This book will be of great interest to graduate and postgraduate students, academics, professionals, and policy makers interested in the field of gender and sexuality in education. It is essential reading for those involved in pre-service and in-service teacher education, diversity education, the sociology of education, as well as education more generally

WORKPLACE EXPERIENCES OF AUSTRALIAN LESBIAN AND GAY TEACHERS: FINDINGS FROM A NATIONAL SURVEY

Historically, lesbian and gay teachers working in schools have experienced silencing, invisibility, and discrimination. This paper reports on research that examined the experiences of self-identified lesbian and gay teachers working in a variety of school types and school systems across Australia. Specifically, it explores these teachers’ experiences of their sexuality in relation to factors associated with enabling or disabling a queer-positive culture and climate in the workplace. Although broader sociol-cultural discourses have increasingly accepted and even celebrated sexual diversity in Australia, especially over the last decade, resulting in a concomitant shift that has improved some employment contexts for some lesbian and gay teachers, this discussion illustrates that many school workplaces continue to produce challenges for staff that are sexuality diverse.

The Elephant in the (Class)Room: Parental Perceptions of LGBTQ-inclusivity in K-12 Educational Contexts

While little is known about parental beliefs and desires regarding LGBTQ-inclusive education, assumptions about these appear to justify teachers’, curriculum writers’ and policy makers’ silences regarding sexuality and gender diversity in the K-12 classroom. Thus, in order to better inform educators’ practices, this paper presents an analysis of interview data from focus groups with parents from across the Australian state of New South Wales. Findings highlight parents’ desires for LGBTQ-inclusivity, not only as a protective factor for sexuality and gender diverse students, but also to engender social cohesion and prepare all students for adult life in the modern social landscape. Parents struggled with the complexities of promoting positive social values through compulsory content while simultaneously respecting diverse sets of values and parents’ rights to frame such topics according to a private set of beliefs. Furthermore, parents advocated for teacher training in this area and were eager for teachers and school leadership staff to feel departmentally-supported to enact LGBTQ-inclusive practices

Gender and Sexuality Diversity in a Culture of Limitation

Gender and Sexuality Diversity in a Culture of Limitation provides an outstanding and insightful critique of the ways that contemporary education is impacted by a range of political, social and cultural influences that inform the approaches that schools take in relation to gender and sexuality diversity. By applying feminist poststructural and Foucauldian frameworks, the book examines the ongoing impact of broader socio-cultural discourse on the lives of gender and sexuality diverse students and teachers. Beginning with an overview of the impact of how a culture of limitation is realised in Australia, the focus moves beyond this context to examine state and federal policies from comparable societies in countries including the USA and the UK and their effect on the production of knowledges and what’s permissible to include in educational curriculum. This research-driven book thus provides a comparative, international overview of the current state of gender and sexuality diversity in schools, and convincingly demonstrates that despite some empowerment of gender and sexuality diverse individuals, silencing and marginalization remain powerful forces. This book will be of great interest to graduate and postgraduate students, academics, professionals, and policy makers interested in the field of gender and sexuality in education. It is essential reading for those involved in pre-service and in-service teacher education, diversity education, the sociology of education, as well as education more generally

What Parents Want: Talking about Gender and Sexuality Diversity in Schools: A Portfolio of Professional Learning Resources for Educators

This output is a portfolio of research-based documents developed from the ARC-funded research "Gender and Sexuality Diversity in Schools: Parental Experiences" (DP18). The portfolio of materials is designed to raise educators' awareness about gender and sexuality diversity, including what Australian public school parents want in terms of inclusion of this topic area in the curriculum and the experiences of parents of gender and sexuality diverse students. The portfolio includes a Facilitator Booklet for in-school training, a Participant Booklet for (teacher/educator) participants; Infographics which visually disseminate the quant/qual findings; and a Playscript which is the basis for the "What Parents Want" 45-min film, a verbatim piece crafted using the words of participating parents

Inclusive pedagogies for transgender and gender diverse children : parents' perspectives on the limits of discourses of bullying and risk in schools

This paper reports on an Australian national investigation of parents of school-aged children attending government schools. The research objective was to ascertain what parents thought in relation to gender and sexuality diversity-related content inclusions in the curriculum, and how a subset of these parents who had a gender and sexuality diverse (GSD) child, experience the public education system for/with their child. Here, we particularly focus on the voices of parents with a transgender or gender-diverse (TGD) child. We examine how these young people are positioned in discourses of risk and safety and how discrimination is depoliticised through bullying discourse. We note how bullying is framed as individualised, leaving broader cisnormative discourses unquestioned. A pedagogy of containment places the burden of gender identity, relationship management and education on the TGD student and family, highlighting a need for more professional development of school personnel

Book Reviews - Breda Čebulj Sajko, Razpotja izseljencev: Razdvojena identiteta avstralskih Slovencev, Ljubljana: Založba ZRC, 2000, 140 pp.

With this publication Čebulj-Sajko has made another important contribution to the hitherto little researched lives and identities of post WWII Slovene immigrants in Australia. This publication comprises the second part of her PhD thesis, Posledice »dvojne identitete« v vsakdanjem življenju avstralskih Slovencev. The first part waspublished in 1999 as Etnologija in izseljenstvo and was, by her own description, a »survey and analysis of published ethnological texts on Slovene em igration between 1926 and 1993, and simultaneously an introduction into the autobiographic method connected with this topic« (Razpotja izseljencev, p. 133). Razpotja izseljencev is an »on-the-ground« exam ination of how »double-ethnic identity« has manifested among Slovenian immigrants in Australia