Direct observation of a uniaxial stress-driven Lifshitz transition in Sr2RuO4

Funding: We gratefully acknowledge support from the European Research Council (Grant No. ERC-714193-QUESTDO), the Royal Society, EPSRC for PhD studentship support through grant number EP/L015110/1 (VS).Pressure represents a clean tuning parameter for traversing the complex phase diagrams of interacting electron systems, and as such has proved of key importance in the study of quantum materials. Application of controlled uniaxial pressure has recently been shown to more than double the transition temperature of the unconventional superconductor Sr2RuO4, leading to a pronounced peak in Tc versus strain whose origin is still under active debate. Here we develop a simple and compact method to passively apply large uniaxial pressures in restricted sample environments, and utilise this to study the evolution of the electronic structure of Sr2RuO4 using angle-resolved photoemission. We directly visualise how uniaxial stress drives a Lifshitz transition of the γ-band Fermi surface, pointing to the key role of strain-tuning its associated van Hove singularity to the Fermi level in mediating the peak in Tc. Our measurements provide stringent constraints for theoretical models of the strain-tuned electronic structure evolution of Sr2RuO4. More generally, our experimental approach opens the door to future studies of strain-tuned phase transitions not only using photoemission but also other experimental techniques where large pressure cells or piezoelectric-based devices may be difficult to implement.Publisher PDFPeer reviewe

Epistemologie der Erziehungswissenschaft: Dilemmas, Fragen, mögliche Lösungen

U radu se polazi od tvrdnje da su epistemološke karakteristike temeljne odrednice znanstvenog digniteta znanosti. Na osnovi kritičke analize epistemoloških karakteristika pedagogije upozorava se na upitnost njezina znanstvenog digniteta. Navedena se tvrdnja obrazlaže odgovorima na nekoliko pitanja: Je li razina razvijenosti suvremenog društva nametnula potrebu redefiniranja semantičkog određenja osnovnih pojmova i pedagogije same? Može li se pedagogija koja desetljećima nije promijenila svoj osnovni teorijski, epistemološko-metodologijski koncept, smatrati suvremenom? Ima li Hrvatska suvremenu pedagogiju ili je riječ o tradicionalnoj (zastarjeloj) pedagogiji? Što je osnovna funkcija pedagogije? Je li pedagogija znanost o odgoju, znanost o odgoju i obrazovanju ili znanost o osposobljavanju ljudi? Jesu li cilj i zadaci pedagogijske znanosti jednoznačno određeni? Na kraju se navode moguća rješenja. Predlažu se nova suvremena jednoznačna semantička određenja temeljnih pojmova i s tog se aspekta utvrđuje osnovna funkcija pedagogije i kao znanstvene i kao praktične discipline, kao teorije osposobljavanja.The argumentation presented in the paper starts from the premise that epistemological characteristics are the elements that science builds its scientific dignity on. A critical analysis of the epistemological characteristics of pedagogy has led the author to question its scientific dignity. The doubts stated in the paper are raised by several questions. Is the level of development of the modern society forcing us to redefine the semantic components of basic pedagogical terms and pedagogy itself? Can pedagogy, which has not changed its basic theoretical, epistemological and methodological concept for decades, really be termed contemporary? Is pedagogy in Croatia contemporary or do we still practice the traditional (and outdated) form of pedagogy? What is the main function of pedagogy? Is pedagogy the science of education, the science of education and development, or the science of human resources development? Are the goals and tasks of pedagogy as a science unambiguously set? Finally, the author suggests possible answers, advocating new, modern and unambiguous semantic definitions of the basic terms, thus determining the primary function of pedagogy as both scientific and practical discipline – a human resources development theory.Den Ausgangspunkt dieser Arbeit bildet die These, dass epistemologische Charakteristiken die wissenschaftliche Dignität jeder Wissenschaft begründen. Anhand einer kritischen Analyse von epistemologischen Charakteristiken der Erziehungswissenschaft wird auf die Fragwürdigkeit ihrer wissenschaftlichen Dignität hingewiesen, Die angeführte Behauptung wird durch Antworten auf einige Fragen erklärt: Macht die Entwicklungsebene der modernen Gesellschaft eine Redefinition der semantischen Bestimmungen pädagogischer Grundbegriffe und der Pädagogik selbst erforderlichß Kann die Erziehungswissenschaft, die seit Jahrzehnten ihr theoretisches, epistemologisch – methodologisches Grundkonzept nicht geändert hat, als modern gelten? Hat Kroatien eine moderne Erziehungswissenschaft oder ob es um eine traditionelle (veraltete) Pädagogik handelt? Was ist die Grundaufgabe der Pädagogik? Ist die Pädagogik eine Wissenschaft über die Erziehung, Wissenschaft über die Erziehung und Bildung oder Wissenschaft über die Befähigung der Menschen? Lassen sich das Ziel und die Aufgaben der Erziehungswissenschaft eindeutig bestimmen? Am Ende werden mögliche Lösungen angeführt. Vorgeschlagen werden neue moderne eindeutige semantische Bestimmungen der pädagogischen Grundbegriffe und von diesem Standpunkt aus Grundaufgaben der Pädagogik sowohl als wissenschaftlicher als auch praktischer Disziplin sowie einer Befähigungstheorie festgelegt

Sn4As3 (dataset)

STM topographies, ARPES data, specific heat measurements and tunneling spectra data of Sn4As3

Data underpinning Peng Ma's thesis

The data files are embargoed until 22/07/202

The exsolution of Cu particles from doped barium cerate zirconate via barium cuprate intermediate phases (dataset)

pape

Dataset underpinning Nikoletta Gkoulemani's thesis

The data files are embargoed until 17/08/202

Metal nanoparticle growth through in situ exsolution from barium cerate zirconate (thesis data)

All the data is in the file type of "*.opj" which can be opened by the software "origin". All the raw data and the relevant plots are also included in these files