Enhanced Superconductivity and Suppression of Charge-density Wave Order in 2H-TaS$_2$ in the Two-dimensional Limit

Yafang Yang; Shiang Fang; Valla Fatemi; Jonathan Ruhman; Efrén Navarro-Moratalla; Kenji Watanabe; Takashi Taniguchi; Efthimios Kaxiras; Pablo Jarillo-Herrero

doi:10.1103/physrevb.98.035203

arXiv · 1711.00079

Enhanced Superconductivity and Suppression of Charge-density Wave Order in 2H-TaS$_2$ in the Two-dimensional Limit

Yafang Yang·Shiang Fang·Valla Fatemi·Jonathan Ruhman·Efrén Navarro-Moratalla·Kenji Watanabe·Takashi Taniguchi·Efthimios Kaxiras·Pablo Jarillo-Herrero

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Abstract

As superconductors are thinned down to the 2D limit, their critical temperature $T_c$ typically decreases. Here we report the opposite behavior, a substantial enhancement of $T_c$ with decreasing thickness, in 2D crystalline superconductor 2H-TaS$_2$. Remarkably, in the monolayer limit, $T_c$ increases to 3.4 K compared to 0.8 K in the bulk. Accompanying this trend in superconductivity, we observe suppression of the charge-density wave (CDW) transition with decreasing thickness. To explain these trends, we perform electronic structure calculations showing that a reduction of the CDW amplitude results in a substantial increase of the density of states at the Fermi energy, which contributes to the enhancement of $T_c$. Our results establish ultra-thin 2H-TaS$_2$ as an ideal platform to study the competition between CDW order and superconductivity.

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Yafang Yang, Shiang Fang, Valla Fatemi, Jonathan Ruhman, Efrén Navarro-Moratalla, Kenji Watanabe, Takashi Taniguchi, Efthimios Kaxiras, Pablo Jarillo-Herrero. 2018-02-27. Enhanced Superconductivity and Suppression of Charge-density Wave Order in 2H-TaS$_2$ in the Two-dimensional Limit. https://doi.org/10.1103/physrevb.98.035203

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