Spatial mapping of the electronic structure of 1T-TaS2

C. Burri,1,2 S. Ekahana,1 R. Venturini,3 E. Della Valle,1 M. Muntwiler,1 V. Strokov,1 A. Barinov,4 G. Aeppli,1,2,5 Y. Ekinci,1 D. Mihailovic,3 S. Gerber1

1Photon Science Division, Paul Scherrer Institut, Villigen PSI, Switzerland

2Department of Physics and Quantum Center, ETH Zurich, Zurich, Switzerland

3Department of Complex Matter, Institut Jožef Stefan, Ljubljana, Slovenia

4Elettra-Sincrotrone Trieste ScPA, Trieste, Italy

5Institut de Physique, EPFL, Lausanne, Switzerland

As a step towards resolving the spatially-resolved electronic structure of the layered transition metal dichalcogenide 1T-TaS2 – and eventually electronically switched cryomemory devices – we have performed angle-resolved photoemission spectroscopy (ARPES). Using a photon energy of 72 eV and the micrometer spot size available at the spectromicroscopy beamline of the Elettra synchrotron, we measured the band structure and high-statistics Fermi surface of 11, 500 and 600 nm thick flakes. Also, the first-order phase transition from the nearly-commensurate to the commensurate CDW state leads to a prominent splitting of the Ta 4f core levels which we have mapped spatially. In addition, using 400 eV soft X-ray ARPES at the ADRESS beamline of the Swiss Light Source synchrotron, we established the kz dependence of the band structure of a 110-nm thick flake, which reveals a two dimensionality of the electronic structure.