A5054292587- Iron-based superconductors research
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Electronic and Structural Properties of Oxides
- Topological Materials and Phenomena
- Rare-earth and actinide compounds
- 2D Materials and Applications
- Magnetic and transport properties of perovskites and related materials
- Graphene research and applications
- High-pressure geophysics and materials
- Magnetic properties of thin films
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Electron and X-Ray Spectroscopy Techniques
- Quantum and electron transport phenomena
- Organic and Molecular Conductors Research
- Advanced Chemical Physics Studies
- Atomic and Molecular Physics
- Copper-based nanomaterials and applications
- Semiconductor materials and devices
- Surface and Thin Film Phenomena
- Cold Atom Physics and Bose-Einstein Condensates
- Corporate Taxation and Avoidance
- Superconductivity in MgB2 and Alloys
- Diamond and Carbon-based Materials Research
Diamond Light Source
2015-2025
Deutsches Elektronen-Synchrotron DESY
2018-2025
London Centre for Nanotechnology
2022
University College London
2022
Hiroshima University
2017-2019
European Synchrotron Radiation Facility
2006-2017
Rutherford Appleton Laboratory
2016
University of Zurich
2001-2009
Japan Atomic Energy Agency
2007-2008
Japan Synchrotron Radiation Research Institute
2005-2006
Improvements in experimental resolution allow this group to elucidate how the electronic nematic transition evolves FeSe. They observe changing Fermi surface, position of lowest energy excitations, as well propensity towards order and its manifestation under strain.
We report the detailed electronic structure of WTe$_2$ by high resolution angle-resolved photoemission spectroscopy. Unlike simple one electron plus hole pocket type Fermi surface topology reported before, we resolved a rather complicated WTe$_2$. Specifically, there are totally nine pockets, including at Brillouin zone center $\Gamma$, and two pockets on each side $\Gamma$ along $\Gamma$-$X$ direction. Remarkably, have observed circular dichroism in our spectra, which suggests that orbital...
We report a combined experimental and theoretical study of the candidate type-II Weyl semimetal MoTe2. Using laser-based angle-resolved photoemission we resolve multiple distinct Fermi arcs on inequivalent top bottom (001) surfaces. All surface states observed experimentally are reproduced by an electronic structure calculation for crystal that predicts topological state with 8 points. further use systematic calculations simulating different point arrangements to discuss robustness...
Abstract Spectroscopic detection of Dirac and Weyl fermions in real materials is vital for both, promising applications fundamental bridge between high-energy condensed-matter physics. While the presence noncentrosymmetric well established many materials, magnetic semimetals still escape direct experimental detection. In order to find a time-reversal symmetry breaking state we design two present here theoretical evidence realization such one them, YbMnBi 2 . We model observed by...
We report angle-resolved photoemission experiments resolving the distinct electronic structure of inequivalent top and bottom (001) surfaces WTe2. On both surfaces, we identify a surface state that forms large Fermi-arc emerging out bulk electron pocket. Using calculations, show these Fermi arcs are topologically trivial their existence is independent presence type-II Weyl points in band structure. This implies observation alone does not allow identification WTe2 as topological semimetal....
The layered van der Waals antiferromagnet MnBi${}_{2}$Te${}_{4}$ has been predicted previously to realize the first intrinsic magnetic topological insulator. Here, authors report spin- and angle-resolved photoemission experiments for MnBi${}_{2}$Te${}_{4}$(0001) surface, revealing a surface state in bulk band gap providing evidence interplay between exchange interaction spin-orbit coupling electronic structure. thus constitutes promising candidate exploit of states order spintronic device concepts.
Altermagnets are an emerging elementary class of collinear magnets. Unlike ferromagnets, their distinct crystal symmetries inhibit magnetization while, unlike antiferromagnets, they promote strong spin polarization in the band structure. The corresponding unconventional mechanism time-reversal symmetry breaking without electronic spectra has been regarded as a primary signature altermagnetism but not experimentally visualized to date. We directly observe structure altermagnetic RuO 2 by...
The free-electron like surface state on the (111) of gold shows a splitting into two parabolic subbands induced by spin orbit interaction. Spin-resolved high-resolution photoemission experiments performed with full three-dimensional polarimeter provide detailed image resulting structure. In particular, spin-resolved momentum distribution maps show that vector lies in plane and is perpendicular to electrons as expected model. This method measuring structure two-dimensional electron gas allows...
We report the spin-selective optical excitation of carriers in inversion-symmetric bulk samples transition metal dichalcogenide (TMDC) ${\mathrm{WSe}}_{2}$. Employing time- and angle-resolved photoelectron spectroscopy (trARPES) complementary time-dependent density functional theory (TDDFT), we observe spin-, valley-, layer-polarized excited state populations upon with circularly polarized pump pulses, followed by ultrafast ($<100\text{ }\text{ }\mathrm{fs}$) scattering towards global...
We report angle resolved photoemission experiments on the electron doped Heisenberg antiferromagnet (Sr(1-x)La(x))(2)IrO(4). For a doping level of x=0.05, we find an unusual metallic state with coherent nodal excitations and antinodal pseudogap bearing strong similarities underdoped cuprates. This emerges from rapid collapse Mott gap resulting in large underlying Fermi surface that is backfolded by (π,π) reciprocal lattice vector which attribute to intrinsic structural distortion Sr(2)IrO(4).
Seismic discontinuities in Earth typically arise from structural, chemical, or temperature variations with increasing depth. The pressure-induced iron spin state transition the lower mantle may influence seismic wave velocities by changing elasticity of iron-bearing minerals, but no seismological evidence an anomaly exists. Inelastic x-ray scattering measurements on (Mg(0.83)Fe(0.17))O-ferropericlase at pressures across show effects limited to only shear moduli elastic tensor. This explains...
A synchrotron radiation beamline in the photon energy range of 18-240 eV and an electron spectroscopy end station have been constructed at 3 GeV Diamond Light Source storage ring. The instrument features a variable polarisation undulator, high resolution monochromator, re-focussing system to form beam spot 50 × μm2, for angle-resolved photoelectron (ARPES) including 6-degrees-of-freedom cryogenic sample manipulator. design its performance allow highly productive precise use ARPES technique...
Recent breakthrough in search for the analogs of fundamental particles condensed matter systems lead to experimental realizations 3D Dirac and Weyl semimetals. state can be hosted either by non-centrosymmetric or magnetic materials first second type. Several have been proposed type-II semimetals, but all them Fermi arcs between projections multiple points not observed directly they were hardly distinguishable from trivial surface states which significantly hinders practical application these...
We study the low-energy surface electronic structure of transition-metal dichalcogenide superconductor PdTe$_2$ by spin- and angle-resolved photoemission, scanning tunneling microscopy, density-functional theory-based supercell calculations. Comparing with its sister compound PtSe$_2$, we demonstrate how enhanced inter-layer hopping in Te-based material drives a band inversion within anti-bonding p-orbital manifold well above Fermi level. show this mediates spin-polarised topological states...
The presence of ${d}_{xz}\text{\ensuremath{-}}{d}_{yz}$ orbital ordering is often considered a hallmark the nematic phase Fe-based superconductors, including FeSe, but details order parameter remain controversial. Here, we report high-resolution angle-resolved photoemission spectroscopy study single crystals accounting for photon-energy dependence and making detailed analysis temperature dependence. We find that hole pocket undergoes fourfold-symmetry-breaking distortion in below 90 K, but,...
We report on the formation of a two-dimensional electron gas (2DEG) at bare surface (111) oriented SrTiO3. Angle resolved photoemission experiments reveal highly itinerant carriers with 6-fold symmetric Fermi and strongly anisotropic effective masses. The electronic structure 2DEG is in good agreement self-consistent tight-binding supercell calculations that incorporate confinement potential due to band bending. further demonstrate alternate exposure ultraviolet light atomic oxygen allows...