Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 42: Charge Order

TT 42.6: Talk

Tuesday, March 13, 2018, 11:30–11:45, HFT-FT 131

Zigzag-chain domain walls facilitate metalisation of the Mott insulator on a triangular lattice — Jan Skolimowski¹ and •Rok Žitko^1,2 — ¹Jožef Stefan Institute, Jamova 39, Ljubljana, Slovenia — ²Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, Ljubljana, Slovenia

Motivated by the occurrence of a long-lived metastable metallic hidden-state in 1T-TaS₂ that can be induced by optical or voltage pulses and that shows a characteristic mosaic pattern of mesoscale charge-density-wave (CDW) domains separated by a dense web of domain walls, we study how the structural domain walls affect the electron dynamics. We consider the Hubbard model on a triangular lattice as a low-energy effective model describing the narrow electron band formed around the Fermi level in the low-temperature commensurate √13 × √13 phase of 1T-TaS₂. Within the effective model a domain wall between two CDW domains leads to a local modification of the hopping constants along a one-dimensional defect line. We study the resulting Hamiltonian using the extension of the dynamical mean-field theory to inhomogeneous systems. We discuss in detail the case where the hopping constants are enhanced and the domain wall metallises. We show that this is facilitated by the fact that in the triangular lattice the domain walls tend to enhance the hopping constants along a connected zigzag line, rather than forming a ladder of dimers which instead show a band gap. We also discuss the case of multiple domain walls and comment on the relevance of the domain-wall-metallisation scenario for the metallic hidden-state.