A5046728214- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Iron-based superconductors research
- Topological Materials and Phenomena
- Graphene research and applications
- Inorganic Fluorides and Related Compounds
- Cold Atom Physics and Bose-Einstein Condensates
- Surface Chemistry and Catalysis
- Superconductivity in MgB2 and Alloys
- Superconducting Materials and Applications
- Corporate Taxation and Avoidance
- Rare-earth and actinide compounds
- Copper-based nanomaterials and applications
- X-ray Diffraction in Crystallography
- Quantum and electron transport phenomena
- Crystal Structures and Properties
- Electronic and Structural Properties of Oxides
- Molecular Junctions and Nanostructures
- Intellectual Capital and Performance Analysis
- Advanced Physical and Chemical Molecular Interactions
- Metallurgical and Alloy Processes
- Surface and Thin Film Phenomena
University of Zurich
2016-2023
We present a soft x-ray angle-resolved photoemission spectroscopy study of overdoped high-temperature superconductors. In-plane and out-of-plane components the Fermi surface are mapped by varying angle incident photon energy. No ${k}_{z}$ dispersion is observed along nodal direction, whereas significant antinodal identified for La-based cuprates. Based on tight-binding parametrization, we discuss implications density states near van Hove singularity. Our results suggest that large electronic...
Abstract A paradigmatic case of multi-band Mott physics including spin-orbit and Hund’s coupling is realized in Ca 2 RuO 4 . Progress understanding the nature this insulating phase has been impeded by lack knowledge about low-energy electronic structure. Here we provide—using angle-resolved photoemission electron spectroscopy—the band structure paramagnetic show how it features several distinct energy scales. Comparison to a simple analysis atomic multiplets provides quantitative estimate J...
Abstract The minimal ingredients to explain the essential physics of layered copper-oxide (cuprates) materials remains heavily debated. Effective low-energy single-band models copper–oxygen orbitals are widely used because there exists no strong experimental evidence supporting multi-band structures. Here, we report angle-resolved photoelectron spectroscopy experiments on La-based cuprates that provide direct observation a two-band structure. This electronic structure, qualitatively...
The molecular ligand pyrphyrin, a tetradentate bipyridine based macrocycle, represents an interesting but widely unexplored class of molecules. It resembles the well-known porphyrin, consists pyridyl subunits instead pyrroles. Metal complexes on pyrphyrin ligands have recently shown promise as water reduction catalysts in homogeneous photochemical splitting reactions. In this study, adsorption and metalation single crystalline Au(111) surface is investigated ultrahigh vacuum by means...
Relativistic massless Dirac fermions can be probed with high-energy physics experiments, but appear also as low-energy quasi-particle excitations in electronic band structures. In condensed matter systems, their nature protected by crystal symmetries. Classification of such symmetry-protected relativistic degeneracies has been fruitful, although many the predicted quasi-particles still await experimental discovery. Here we reveal, using angle-resolved photoemission spectroscopy, existence...
A comprehensive angle-resolved photoemission spectroscopy study of the band structure in single-layer cuprates is presented with aim uncovering universal trends across different materials. Five hole- and electron-overdoped cuprate superconductors (${\mathrm{La}}_{1.59}{\mathrm{Eu}}_{0.2}{\mathrm{Sr}}_{0.21}{\mathrm{CuO}}_{4}$, ${\mathrm{La}}_{1.77}{\mathrm{Sr}}_{0.23}{\mathrm{CuO}}_{4}$, ${\mathrm{Bi}}_{1.74}{\mathrm{Pb}}_{0.38}{\mathrm{Sr}}_{1.88}{\mathrm{CuO}}_{6+\ensuremath{\delta}}$,...
We present a comprehensive angle-resolved photoemission spectroscopy study of ${\mathrm{Ca}}_{1.8}{\mathrm{Sr}}_{0.2}{\mathrm{RuO}}_{4}$. Four distinct bands are revealed and along the Ru-O bond direction their orbital characters identified through light polarization analysis comparison to dynamical mean-field theory calculations. Bands assigned ${d}_{xz},{d}_{yz}$ orbitals display Fermi liquid behavior with fourfold quasiparticle mass renormalization. Extremely heavy fermions---associated...
Abstract Electronic band structures in solids stem from a periodic potential reflecting the structure of either crystal lattice or electronic order. In stoichiometric ruthenate Ca 3 Ru 2 O 7 , numerous Fermi surface-sensitive probes indicate low-temperature reconstruction. Yet, causality and reconstructed remain unsolved. Here, we show by angle-resolved photoemission spectroscopy, how C -symmetric massive Dirac semimetal is realized through Brillouin-zone preserving This emerges two-stage...
We present a combined soft x-ray and high-resolution vacuum-ultraviolet angle-resolved photoemission spectroscopy study of the electron-overdoped cuprate ${\mathrm{Pr}}_{1.3\ensuremath{-}x}{\mathrm{La}}_{0.7}{\mathrm{Ce}}_{x}{\mathrm{CuO}}_{4}$ (PLCCO). Demonstration its highly two-dimensional band structure enabled precise determination in-plane self-energy dominated by electron-electron scattering. Through analysis this Fermi liquid cut-off energy scale, we find---in contrast to hole-doped...
Doped Mott insulators are the starting point for interesting physics such as high temperature superconductivity and quantum spin liquids. For multi-band insulators, orbital selective ground states have been envisioned. However, metals difficult to realize experimentally. Here we demonstrate by photoemission spectroscopy how Ca$_2$RuO$_4$, upon alkali-metal surface doping, develops a single-band metal skin. Our dynamical mean field theory calculations reveal that homogeneous electron doping...
We carried out a comprehensive high-resolution angle-resolved photoemission spectroscopy (ARPES) study of the pseudogap interplay with superconductivity in La-based cuprates. The three systems La2−xSrxCuO4, La1.6−xNd0.4SrxCuO4, and La1.8−xEu0.2SrxCuO4 display slightly different critical points temperature versus doping phase diagram. studied evolution into superconducting state for concentrations just below point. In this setting, near optimal presence weakest possible pseudogap, we uncover...
Two-dimensional semimetals have been the center of intensified investigations since realization graphene. In particular, design Dirac and Weyl has scrutinized. Typically, metals emerge from crystal-field environments captured by density functional theory (DFT). Here, we show angle-resolved photoemission spectroscopy (ARPES) how a rotational symmetry broken massive semimetal is realized in Ca3Ru2O7. This emerges two-stage electronic transition driven electron correlations beyond DFT paradigm....
The unified modeling of iron-based high-temperature superconductors has been complicated by different phenomenologies in the iron-pnictides and iron-chalcogenides. Here we use x-ray diffraction angle-resolved photoemission spectroscopy to investigate lattice electronic properties Pr4Fe2As2Te0.88O4 (Tc=25 K) superconductor. crystal structure undergoes a (Ts=250 orthorhombic transition with no apparent magnetic transition. Further, find Fermi surface consist zone-corner electron pockets only....
We have carried out a comprehensive high-resolution angle-resolved photoemission spectroscopy (ARPES) study of the pseudogap interplay with superconductivity in La-based cuprates. The three systems La$_{2-x}$Sr$_x$CuO$_4$, La$_{1.6-x}$Nd$_{0.4}$Sr$_x$CuO$_4$, and La$_{1.8-x}$Eu$_{0.2}$Sr$_x$CuO$_4$ display slightly different critical points temperature versus doping phase diagram. studied evolution into superconducting state for concentrations just below point. In this setting, near optimal...
The interplay of structural and electronic phases in iron-based superconductors is a central theme the search for superconducting pairing mechanism. While nematicity, defined as breaking four-fold symmetry triggered by degrees freedom, competing with superconductivity, effect purely orthorhombic order unexplored. Here, using x-ray diffraction (XRD), we reveal new phase an exceptionally high onset temperature ($T_\mathrm{ort} \sim 250$ K), which coexists superconductivity ($T_\mathrm{c} = 25$...