Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 86: Low-Dimensional Systems: Charge Order

TT 86.2: Talk

Friday, March 24, 2017, 11:30–11:45, HSZ 103

Electronic self-organization in layered transition metal dichalcogenides — •Tobias Ritschel¹, Jan Trinckauf², Martin von Zimmermann³, Klaus Koepernik², Peter Abbamonte⁵, Young Joe⁵, Helmuth Berger⁴, Bernd Büchner^1,2, and Jochen Geck¹ — ¹TU Dresden — ²IFW, Dresden — ³DESY Hamburg — ⁴Ecole polytechnique Federale de Lausanne — ⁵University of Illinois

We combined density functional theory (DFT) with angle-resolved photoemission spectroscopy (ARPES) and x-ray diffraction to discover that the electronic order in the prototypical charge density wave system 1T-TaS₂ involves complex orbital textures. Most importantly, the low energy electronic band structure parallel to the layers depends crucially on the stacking of these orbital textures in the perpendicular direction, which challenges the classical view of these materials as being quasi 2D-systems. Recently, we refined our DFT models to implement an approximation of the partially disordered character, which is found experimentally for the orbital texture stacking in the so-called Mott-phase of 1T-TaS₂. The excellent agreement of these simulations with ARPES data indicates that the previous paradigm of a Mott-gap in this system needs to be reconsidered. Instead, we find firm evidence that the corresponding gap is predominantly caused by hybridization between the orbital textures in adjacent TaS₂-layers. We will discuss these results with respect to recent experiments which reported marked changes of macroscopic properties in exfoliated transition metal dichalcogenides as a function of thickness. Understanding such effects is increasingly important with respect to future applications.