Photoinduced Dynamics of Commensurate Charge Density Wave in 1T-TaS2 Based on Three-Orbital Hubbard Model

Tatsuhiko Ikeda,Kenji Yonemitsu,Hirokazu Tsunetsugu

doi:10.3390/app9010070

Tatsuhiko Ikeda, Kenji Yonemitsu + Show 1 more

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https://doi.org/10.3390/app9010070

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Journal: Applied sciences	Publication Date: Dec 25, 2018
Citations: 5	License type: CC BY 4.0

Affiliation: The University of Tokyo, Chuo University

Abstract

We study the coupled charge-lattice dynamics in the commensurate charge density wave (CDW) phase of the layered compound 1T-TaS 2 driven by an ultrashort laser pulse. For describing its electronic structure, we employ a tight-binding model of previous studies including the effects of lattice distortion associated with the CDW order. We further add on-site Coulomb interactions and reproduce an energy gap at the Fermi level within a mean-field analysis. On the basis of coupled equations of motion for electrons and the lattice distortion, we numerically study their dynamics driven by an ultrashort laser pulse. We find that the CDW order decreases and even disappears during the laser irradiation while the lattice distortion is almost frozen. We also find that the lattice motion sets in on a longer time scale and causes a further decrease in the CDW order even after the laser irradiation.

Highlights

Transition-metal dichalcogenides (TMDs) are layered compounds that are a testbed to study electron correlations and electron–lattice interactions in two dimensions [1,2,3]
The commensurate CDW (CCDW) phase is insulating as revealed by early resistivity and susceptibility measurements [1], and this is confirmed by recent experiments of angle-resolved photo-emission spectroscopy (ARPES) [9]
We have further extended the model to treat the lattice distortion as a dynamical variable

Summary

Introduction

Transition-metal dichalcogenides (TMDs) are layered compounds that are a testbed to study electron correlations and electron–lattice interactions in two dimensions [1,2,3]. Photoexcitation [20,21,22,23,24] and a gate-voltage pulse [25,26,27,28] have realized transitions to metastable states, which are often referred to as hidden states [29,30,31]. Since these states are quite stable, the phase transitions have potential application to nonvolatile ultrafast memory devices [26,28,32]

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