Kavli Affiliate: Feng Yuan
| First 5 Authors: Changhua Bao, Haoyuan Zhong, Shaohua Zhou, Runfa Feng, Yuan Wang
| Summary:
Time- and angle-resolved photoemission spectroscopy (TrARPES) is a powerful
technique for capturing the ultrafast dynamics of charge carriers and revealing
photo-induced phase transitions in quantum materials. However, the lack of
widely tunable probe photon energy, which is critical for accessing the
dispersions at different out-of-plane momentum $k_z$ in TrARPES measurements,
has hindered the ultrafast dynamics investigation of 3D quantum materials such
as Dirac or Weyl semimetals. Here we report the development of a TrARPES system
with a highly tunable probe photon energy from 5.3 to 7.0 eV. The tunable probe
photon energy is generated by the fourth harmonic generation of a tunable
wavelength femtosecond laser source by combining a $beta$-BaB$_2$O$_4$ (BBO)
crystal and a KBe$_2$BO$_3$F$_2$ (KBBF) crystal. High energy resolution of 29 –
48 meV and time resolution of 280 – 320 fs are demonstrated on 3D topological
materials ZrTe$_5$ and Sb$_2$Te$_3$. Our work opens up new opportunities for
exploring ultrafast dynamics in 3D quantum materials.
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