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Nano ARPES on 4H -TaS2

We observed contrast in Ta4f 7/2 line between 1T and 2H crystallographic domains on TaS2. There is a sharp transition between the charge-density-wave splitted spin-orbit component on the 1T domain and the single feature on the 2H domain. D. Rahn, K. Rossnagel, S. Hellmann, C. Sohrt, L. Kipp, Institute of Experimental and Applied Physics, University of Kiel, Germany.

Angle-resolved photoelectron nano-spectroscopy of a 4Hb-TaS2 surface. (a) Imaging of the domain structure using the Ta 4f 7/2 core level for intensity contrast. The used imaging energy is marked with a red line in (b). (b) Spatially resolved spectra of the Ta 4f 7/2 along the red line in (a). There is a sharp transition between the charge-density-wave splitted spin-orbit component on the 1T domain and the single feature on the 2H domain. (c) ARPES spectrum (binding energy vs. wave vector parallel to the surface) taken at the blue dot in (a) (1T domain). The cut through the electron pocket around the ГM point (in the second Brillouin zone) shows the expected features. First, large parts of the spectral weight are shifted away from the Fermi level to higher binding energies and a gap of approximately 200 meV has opened. Second, around 2.7 °A−1 a shadow band can be observed (marked by the black doted ellipsis) which is due to the additional periodicity of the charge density-wave in the 1T layer. (d) ARPES spectrum taken at the green dot in (a) (2H-domain) shows a cut along the ГK-direction.On the left side in the image the double-walled boundary of the K-pocket (see black dotted lines as guides to the eye) is resolved, which is typical for the 2H polytype. Remarkably, the 2H layer does not show an energy gap around EF and remains in the metallic state. In conclusion, the data show strong indication that there is a coexistence of two distinctly different electronic structures on the micron scale.

Unpublished
Last Updated on Tuesday, 28 April 2015 11:36