Three-Dimensional Fermi-Surface Nesting in 1T-VSe2Studied by Angle-Resolved Photoemission Spectroscopy

We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) with synchrotron radiation on layered transition-metal dichalcogenide 1 T -VSe 2 to study the mechanism of the three-dimensional charge-density-wave (CDW) transition. We found that the Fermi surface around the M(L) and K(H) points shows considerable wiggling along the wave vector normal to the layer ( k z ) despite the apparently two-dimensional crystal structure. ARPES spectra below the CDW transition temperature show a signature of pseudogap opening at a specific k z -region on the Fermi surface, demonstrating that the CDW transition of 1 T -VSe 2 is driven by three-dimensional Fermi-surface nesting.