Roles of the Narrow Electronic Band near the Fermi Level in 1 T − TaS 2 -Related Layered Materials

作者：Chenhaoping Wen, Jingjing Gao, Yuan Xie, Qing Zhang, Pengfei Kong, Jinghui Wang, Yilan Jiang, Xuan Luo, Jun Li, W. J. Lu, Yuping Sun, Shichao Yan · 发表于：Physical Review Letters · 年份：2021 · DOI：10.1103/physrevlett.126.256402 · 被引用次数：55 · 研究领域：Chalcogenide Semiconductor Thin Films、2D Materials and Applications、Electronic and Structural Properties of Oxides

Here we use low-temperature scanning tunneling microscopy and spectroscopy to reveal the roles of the narrow electronic band in two $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$-related materials (bulk $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ and $4{H}_{\mathrm{b}}\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$). $4{H}_{\mathrm{b}}\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ is a superconducting compound with alternating $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ and $1H\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ layers, where the $1H\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ layer has a weak charge density wave (CDW) pattern and reduces the CDW coupling between the adjacent $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ layers. In the $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ layer of $4{H}_{\mathrm{b}}\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$, we observe a narrow electronic band located near the Fermi level, and its spatial distribution is consistent with the tight-binding calculations for two-dimensional $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ layers. The weak electronic hybridization between the $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ and $1H\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ layers in $4{H}_{\mathrm{b}}\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ shifts the narrow electronic band to be slightly above the Fermi level, which suppresses the electronic correlation-induced band splitting. In contrast, in bulk $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$, there is an interlayer CDW c...