AVS 52nd International Symposium
    Surface Science Friday Sessions
       Session SS2-FrM

Paper SS2-FrM1
Three-Dimensional Valence Band Structure of WTe@sub 2@

Friday, November 4, 2005, 8:20 am, Room 203

Session: Electronic Structure of Surfaces
Presenter: T. Ohta, Lawrence Berkeley National Laboratory/Fritz Haber Institute
Authors: T. Ohta, Lawrence Berkeley National Laboratory/Fritz Haber Institute
A. Bostwick, Lawrence Berkeley National Laboratory
E. Rotenberg, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
We report complete valence band structure measurement of tungsten ditelluride (WTe@sub 2@) in 3-dimensions (3D) of k-space by angle-resolved photoemission spectroscopy (ARPES). WTe@sub 2@ is comprised of Te-W-Te layers, and is known to exhibit semi-metallic conduction. Unlike most transition metal dichalcogenide compounds, WTe@sub 2@ has an orthorhombic unit cell. It was previously shown by density-function-theory calculation that WTe@sub 2@ has a metallic band in addition to a semi-metallic band, which is brought about by W 5d and Te 5p bands overlapping near the Fermi-level (E@sub F@). So far, the parallel existence of semi-metallic and metallic bands has not been clearly demonstrated in photoemission experiments due to a complex overlap of W 5d and Te 5p derived states, and because of their k@sub z@ (k perpendicular) dependence near E@sub F@. To shed light on this issue, we have conducted complete 3D band structure mapping of WTe@sub 2@ using synchrotron radiation ARPES. 3D band structure mapping is a powerful tool for investigating the entire electronic structure of a material by visualizing valence band in all three k directions. We have clearly observed the semi-metallic and the metallic bands crossing E@sub F@, and the k@sub z@ dependence of both semi-metallic and metallic bands especially close to E@sub F@. While the semi-metallic band has a slight k@sub z@ dependence, the metallic band appears only near the zone center. We compare our measured 3D band structure to the reported band structure calculation with emphasis on the Fermi surface contour. The semi-metallic conduction can be attributed to the semi-metallic band existing throughout the k@sub z@ direction, whereas the metallic band is limited to the zone center.