title: Three-dimensional electron realm in VSe2 by soft-x-ray photoelectron spectroscopy: origin of charge-density waves.
abstract: The resolution of angle-resolved photoelectron spectroscopy (ARPES) in three-dimensional (3D) momentum k is fundamentally limited by ill defined surface-perpendicular wave vector k(perpendicular) associated with the finite photoelectron mean free path. Pushing ARPES into the soft-x-ray energy region sharpens the k(perpendicular) definition, allowing accurate electronic structure investigations in 3D materials. We apply soft-x-ray ARPES to explore the 3D electron realm in a paradigm transition metal dichalcogenide VSe2. Essential to break through the dramatic loss of the valence band photoexcitation cross section at soft-x-ray energies is the advanced photon flux performance of our synchrotron instrumentation. By virtue of the sharp 3D momentum definition, the soft-x-ray ARPES experimental band structure and Fermi surface of VSe2 show a textbook clarity. We identify pronounced 3D warping of the Fermi surface and show that its concomitant nesting acts as the precursor for the exotic 3D charge-density waves in VSe2. Our results demonstrate the immense potential of soft-x-ray ARPES to explore details of 3D electronic structure.
authors.affiliation: Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen-PSI, Switzerland. vladimir.strocov@psi.ch
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Strocov
authors.forename: Ming
authors.initials: M
authors.lastname: Shi
authors.forename: Masaki
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Claude
authors.initials: C
authors.lastname: Monney
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Wang
authors.forename: Juraj
authors.initials: J
authors.lastname: Krempasky
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schmitt
authors.forename: Luc
authors.initials: L
authors.lastname: Patthey
authors.forename: Helmuth
authors.initials: H
authors.lastname: Berger
authors.forename: Peter
authors.initials: P
authors.lastname: Blaha