Angle-resolved photoemission spectroscopy
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Magnetic Weyl semimetal phase in a Kagomé crystal Open
Magnetic Weyl semimetals Weyl semimetals (WSMs)—materials that host exotic quasiparticles called Weyl fermions—must break either spatial inversion or time-reversal symmetry. A number of WSMs that break inversion symmetry have been identifi…
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Angle-resolved photoemission studies of quantum materials Open
The physics of quantum materials is dictated by many-body interactions and mathematical concepts such as symmetry and topology that have transformed our understanding of matter. Angle-resolved photoemission spectroscopy (ARPES), which dire…
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Lorentz-violating type-II Dirac fermions in transition metal dichalcogenide PtTe2 Open
Topological semimetals have recently attracted extensive research interests as host materials to condensed matter physics counterparts of Dirac and Weyl fermions originally proposed in high energy physics. Although Lorentz invariance is re…
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Determination of band offsets, hybridization, and exciton binding in 2D semiconductor heterostructures Open
Photoemission measurements on exfoliated 2D heterostructures reveal detailed electronic structure and hybridization effects.
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Evidence for superconductivity in Li-decorated monolayer graphene Open
Significance Although superconductivity is well-known in intercalated bulk graphite, the ultimate goal of inducing superconductivity in single-layer graphene has not yet been achieved. We have here developed an experiment that combines ult…
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Observation of flat bands in twisted bilayer graphene Open
Transport experiments in twisted bilayer graphene have revealed multiple superconducting domes separated by correlated insulating states1–5. These properties are generally associated with strongly correlated states in a flat mini-band of t…
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Femtosecond electron-phonon lock-in by photoemission and x-ray free-electron laser Open
A deeper look into iron selenide In the past 10 years, iron-based superconductors have created more puzzles than they have helped resolve. Some of the most fundamental outstanding questions are how strong the interactions are and what the …
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Epitaxial Graphene on SiC: A Review of Growth and Characterization Open
This review is devoted to one of the most promising two-dimensional (2D) materials, graphene. Graphene can be prepared by different methods and the one discussed here is fabricated by the thermal decomposition of SiC. The aim of the paper …
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Band Alignments, Valence Bands, and Core Levels in the Tin Sulfides SnS, SnS<sub>2</sub>, and Sn<sub>2</sub>S<sub>3</sub>: Experiment and Theory Open
Tin sulfide solar cells show relatively poor efficiencies despite attractive photovoltaic properties, and there is difficulty in identifying separate phases, which are also known to form during Cu2ZnSnS4 depositions. We present X-ray photo…
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Emergence of a Metal–Insulator Transition and High-Temperature Charge-Density Waves in VSe<sub>2</sub> at the Monolayer Limit Open
Emergent phenomena driven by electronic reconstructions in oxide heterostructures have been intensively discussed. However, the role of these phenomena in shaping the electronic properties in van der Waals heterointerfaces has hitherto not…
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Common electronic origin of superconductivity in (Li,Fe)OHFeSe bulk superconductor and single-layer FeSe/SrTiO3 films Open
The mechanism of high-temperature superconductivity in the iron-based superconductors remains an outstanding issue in condensed matter physics. The electronic structure plays an essential role in dictating superconductivity. Recent revelat…
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Discovery of Orbital Selective Cooper Pairing in FeSe Open
FeSe is the focus of intense research interest because of its unusual non-magnetic nematic state and because it forms the basis for achieving the highest critical temperatures of any iron-based superconductor. However, its Cooper pairing m…
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Quadratic Fermi node in a 3D strongly correlated semimetal Open
Strong spin–orbit coupling fosters exotic electronic states such as topological insulators and superconductors, but the combination of strong spin–orbit and strong electron–electron interactions is just beginning to be understood. Central …
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Criteria for Directly Detecting Topological Fermi Arcs in Weyl Semimetals Open
The recent discovery of the first Weyl semimetal in TaAs provides the first observation of a Weyl fermion in nature and demonstrates a novel type of anomalous surface state, the Fermi arc. Like topological insulators, the bulk topological …
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Interfacial electronic structure at the CH3NH3PbI3/MoOx interface Open
Interfacial electronic properties of the CH3NH3PbI3 (MAPbI3)/MoOx interface are investigated using ultraviolet photoemission spectroscopy and X-ray photoemission spectroscopy. It is found that the pristine MAPbI3 film coated onto the subst…
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Topological insulators, topological superconductors and Weyl fermion semimetals: discoveries, perspectives and outlooks Open
Here, unlike string theory, topological physics in lower dimensional condensed matter systems is an experimental reality since the bulk-boundary correspondence can be probed experimentally in lower dimensions. In addition, recent experimen…
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Quantum transport in Dirac and Weyl semimetals: a review Open
Topological semimetals are well known for the linear energy band dispersion in the bulk state and topologically protected surface state with arc-like Fermi surface. The angle resolved photoemission spectroscopy experiments help confirm the…
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A facility for the analysis of the electronic structures of solids and their surfaces by synchrotron radiation photoelectron spectroscopy Open
A synchrotron radiation beamline in the photon energy range of 18-240 eV and an electron spectroscopy end station have been constructed at the 3 GeV Diamond Light Source storage ring. The instrument features a variable polarisation undulat…
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Energy-dependent photoemission delays from noble metal surfaces by attosecond interferometry Open
How quanta of energy and charge are transported on both atomic spatial and ultrafast time scales is at the heart of modern technology.Recent progress in ultrafast spectroscopy has allowed us to directly study the dynamical response of an e…
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Momentum-dependent sign inversion of orbital order in superconducting FeSe Open
We investigate the electronic reconstruction across the tetragonal-orthorhombic structural transition in FeSe by employing polarization-dependent angle-resolved photoemission spectroscopy (ARPES) on detwinned single crystals. Across the st…
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Review of 2D superconductivity: the ultimate case of epitaxial monolayers Open
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Signatures of a time-reversal symmetric Weyl semimetal with only four Weyl points Open
Through intense research on Weyl semimetals during the past few years, we have come to appreciate that typical Weyl semimetals host many Weyl points. Nonetheless, the minimum nonzero number of Weyl points allowed in a time-reversal invaria…
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Coexistence of Charge-Density-Wave and Pair-Density-Wave Orders in Underdoped Cuprates Open
We analyze incommensurate charge-density-wave (CDW) and pair-density-wave (PDW) orders with transferred momenta (±Q,0)/(0,±Q) in underdoped cuprates within the spin-fermion model. Both orders appear due to an exchange of spin fluctuations …
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Photoemission Spectroscopy Characterization of Halide Perovskites Open
Controlling the surface and interface properties of halide perovskites (HaPs) materials is key to improve performance and stability of HaP‐based optoelectronic devices such as solar cells. Here, an overview is given on the use of different…
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Tracking Primary Thermalization Events in Graphene with Photoemission at Extreme Time Scales Open
Direct and inverse Auger scattering are amongst the primary processes that mediate the thermalization of hot carriers in semiconductors. These two processes involve the annihilation or generation of an electron-hole pair by exchanging ener…
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Spin–orbit coupling in the band structure of monolayer WSe<sub>2</sub> Open
We used angle-resolved photoemission spectroscopy (ARPES) to map out the band structure of single-layer WSe2. The splitting of the top of the valence band because of spin-orbit coupling is 513 ± 10 meV, in general agreement with theoretica…
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Carrier‐Density Control of the SrTiO<sub>3</sub> (001) Surface 2D Electron Gas studied by ARPES Open
The origin of the 2D electron gas (2DEG)stabilized at the bare surface of SrTiO3 (001) is investigated. Using high-resolution angle-resolved photoemission and core-level spectroscopy, it is shown conclusively that this 2DEG arises from lig…
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Strain Control of Fermiology and Many-Body Interactions in Two-Dimensional Ruthenates Open
Here we demonstrate how the Fermi surface topology and quantum many-body interactions can be manipulated via epitaxial strain in the spin-triplet superconductor Sr_{2}RuO_{4} and its isoelectronic counterpart Ba_{2}RuO_{4} using oxide mole…
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Photoemission perspective on pseudogap, superconducting fluctuations, and charge order in cuprates: a review of recent progress Open
In the course of seeking the microscopic mechanism of superconductivity in cuprate high temperature superconductors, the pseudogap phase- the very abnormal 'normal' state on the hole-doped side- has proven to be as big of a quandary as sup…
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Distinctive orbital anisotropy observed in the nematic state of a FeSe thin film Open
Nematic state, where the system is translationally invariant but breaks the rotational symmetry, has drawn great attentions recently due to experimental observations of such a state in both cuprates and iron-based superconductors. The mech…