0000000000385342
AUTHOR
Yves Acremann
Observation of an excitonic Mott transition through ultrafast core-cum-conduction photoemission spectroscopy
Time-resolved soft-X-ray photoemission spectroscopy is used to simultaneously measure the ultrafast dynamics of core-level spectral functions and excited states upon excitation of excitons in WSe$_2$. We present a many-body approximation for the Green's function, which excellently describes the transient core-hole spectral function. The relative dynamics of excited-state signal and core levels reveals a delayed core-hole renormalization due to screening by excited quasi-free carriers, revealing an excitonic Mott transition. These findings establish time-resolved core-level photoelectron spectroscopy as a sensitive probe of subtle electronic many-body interactions and an ultrafast electronic…
Compact setup for spin-, time-, and angle-resolved photoemission spectroscopy.
Review of scientific instruments 91(6), 063001 (2020). doi:10.1063/5.0004861
Imaging spin filter for electrons based on specular reflection from iridium (001)
Abstract As Stern–Gerlach type spin filters do not work with electrons, spin analysis of electron beams is accomplished by spin-dependent scattering processes based on spin–orbit or exchange interaction. Existing polarimeters are single-channel devices characterized by an inherently low figure of merit (FoM) of typically 10 −4 –10 −3 . This single-channel approach is not compatible with parallel imaging microscopes and also not with modern electron spectrometers that acquire a certain energy and angular interval simultaneously. We present a novel type of polarimeter that can transport a full image by making use of k -parallel conservation in low-energy electron diffraction. We studied specul…
4D texture of circular dichroism in soft-x-ray photoemission from tungsten
Brief treatment and crisis intervention 21(1), 013017 (2019). doi:10.1088/1367-2630/aaf4cd
Direct 3D mapping of the Fermi surface and Fermi velocity.
Time-of-flight momentum microscopy is developed. It enables direct three-dimensional mapping of the topology of the Fermi surface, identification of electron and hole pockets, and quantification of Fermi velocity as a function of wavevector.
Time-resolved core-level photoemission data of tungsten diselenide
Pump-probe core-level photoemission spectroscopy data of tungsten diselenide (WSe2) measured using an electron momentum microscope at the FLASH Free-electron laser.