Manipulating charge-density-wave in $1T$-TaS$_{2}$ by charge carrier doping: A first-principles investigation

TL;DR

This study uses first-principles calculations to explore how charge carrier doping influences charge density wave states in $1T$-TaS$_{2}$, revealing mechanisms for manipulating its electronic phases and potential superconductivity.

Contribution

It provides a detailed first-principles analysis of doping effects on CCDW stability and phase transitions in $1T$-TaS$_{2}$, highlighting different impacts of electron and hole doping.

Findings

Electron doping stabilizes CCDW in bulk and monolayer $1T$-TaS$_{2}$.

Hole doping suppresses CCDW and can induce superconductivity with $T_{c}$ of 6-7 K.

Electric field-induced doping can switch between CCDW, NCCDW, and metallic states.

Abstract

The transition metal dichalcogenide (TMD) $1T$-TaS$_{2}$ exhibits a rich set of charge density wave (CDW) orders. Recent investigations suggested that using light or electric field can manipulate the commensurate (C) CDW ground state. Such manipulations are considered to be determined by the charge carrier doping. Here we simulate by first-principles calculations the carrier doping effect on CCDW in $1T$-TaS$_{2}$. We investigate the charge doping effects on the electronic structures and phonon instabilities of $1T$ structure and analyze the doping induced energy and distortion ratio variations in CCDW structure. We found that both in bulk and monolayer $1T$-TaS$_{2}$, CCDW is stable upon electron doping, while hole doping can significantly suppress the CCDW, implying different mechanisms of such reported manipulations. Light or positive perpendicular electric field induced hole doping increases the energy of CCDW, so that the system transforms to NCCDW or similar metastable state. On the other hand, even the CCDW distortion is more stable upon in-plain electric field induced electron injection, some accompanied effects can drive the system to cross over the energy barrier from CCDW to nearly commensurate (NC) CDW or similar metastable state. We also estimate that hole doping can introduce potential superconductivity with $T_{c}$ of $6\sim7$ K. Controllable switching of different states such as CCDW/Mott insulating state, metallic state, and even the superconducting state can be realized in $1T$-TaS$_{2}$, which makes the novel material have very promising applications in the future electronic devices.