Time- and Polarization-Resolved Extreme Ultraviolet Momentum Microscopy

TL;DR

This paper introduces a novel ultrafast, polarization-tunable XUV momentum microscope capable of time- and angle-resolved photoemission spectroscopy, enabling detailed studies of quantum materials' electronic structures in out-of-equilibrium conditions.

Contribution

The development of an advanced momentum microscope with multimodal dichroism capabilities and high spatial, energy, and temporal resolution for quantum material investigations.

Findings

Achieved 44 meV energy resolution and 144 fs temporal resolution.

Demonstrated dichroism measurements in photoelectron angular distributions.

Enabled comprehensive momentum-resolved studies of quantum materials.

Abstract

We report the development of an instrument combining an ultrafast, high-repetition-rate, polarization-tunable monochromatic extreme ultraviolet (XUV, 21.6 eV) beamline and a next-generation momentum microscope endstation. This setup enables time- and angle-resolved photoemission spectroscopy of quantum materials, offering multimodal photoemission dichroism capabilities. The momentum microscope simultaneously detects the full surface Brillouin zone over an extended binding energy range. It is equipped with advanced electron optics, including a new type of front lens that supports multiple operational modes. Enhanced spatial resolution is achieved by combining the small XUV beam footprint (33 $\mu$m by 45 $\mu$m) with the selection of small regions of interest using apertures positioned in the Gaussian plane of the momentum microscope. This instrument achieves an energy resolution of 44 meV and a temporal resolution of 144 fs. We demonstrate the capability to perform linear, Fourier, and circular dichroism in photoelectron angular distributions from photoexcited 2D materials. This functionality paves the way for time-, energy-, and momentum-resolved investigations of orbital and quantum geometrical properties underlying electronic structures of quantum materials driven out of equilibrium.