Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 46: 2D Materials beyond Graphene: TMDCs, Slicene and Relatives

O 46.12: Poster

Dienstag, 8. März 2016, 18:15–20:30, Poster E

Angle-resolved photoemission spectroscopy of the possible chiral charge-density-wave state of 1T-TiSe₂ — •Sascha Beier, Matthias Kallaene, Arndt Quer, and Kai Rossnagel — Institute of Experimental and Applied Physics, University of Kiel, 24098 Kiel, Germany

The layered transition-metal dichalcogenide 1T-TiSe₂ undergoes a transition into a commensurate 2× 2× 2 triple-q charge-density-wave (CDW) state at a temperature of ≈ 200 K. Recently, Ishioka et al. discovered a possible chiral CDW phase employing scanning tunneling microscopy (STM) below 85 K. Castellan et al. determined the transition temperature to this chiral CDW phase to be 7 K below the transition temperature into the normal CDW phase by specific heat, electrical transport properties, and X-ray diffraction measurements. However, a recent STM study questions the existence of an intrinsically chiral CDW state. Novello et al. rather attribute the effect to native lattice defects and the substitution of atoms.

Here we present angle-resolved photoelectron spectroscopy (ARPES) data on 1T-TiSe₂ utilizing circular polarized synchrotron radiation. In the CDW phase, the electronic structure is characterized by a strong backfolding of the Se 4p-derived bands to the L-point. Dichroism ARPES measurements of this spectroscopic order parameter at the L point apper to be consistent with the emergence of a chiral CDW state at temperatures below 190 K, in good agreement with the results of Castellan et al.