论文标题
通过在二维金属中通过范霍夫奇异性调音，超导圆顶
Superconducting dome by tuning through a Van Hove singularity in a two-dimensional metal
论文作者
论文摘要
化学替代是探索低维量子材料中各种兴奋剂和/或疾病依赖性集体现象的有前途的途径。在这里，我们表明过渡金属二甲基化合物合金是实现此目的的理想平台。特别是，我们证明了在原本金属的单层Tase $ _ {2} $中通过替代W原子提供的分钟电子掺杂的出现。我们使用可变温度（0.34 K-4.2 K）扫描隧道隧道频谱（STS）研究了TA $ _ {1-δ} $_δ$ se $ _2 $的超导状态的温度和磁场依赖性。我们揭示了超导圆顶的出现，跨度为0.003 <$δ$ <0.03，最大化的临界温度为0.9 k，与散装tase $ _ {2} $（t $ _c $ = 0.14 K）的临界温度最大化。当费米表面接近范霍夫（Van Hove）奇异性时，超导性来自状态密度的增加（DOS）。但是，一旦达到奇异性，DOS就会以$δ$降低，从而逐渐削弱了超导状态，从而塑造了超导圆顶。最后，我们的兴奋剂依赖性测量值使我们能够明确地跟踪由W掺杂剂引起的疾病触发的库仑玻璃相的发展。
Chemical substitution is a promising route for the exploration of a rich variety of doping- and/or disorder-dependent collective phenomena in low-dimensional quantum materials. Here we show that transition metal dichalcogenide alloys are ideal platforms to this purpose. In particular, we demonstrate the emergence of superconductivity in the otherwise metallic single-layer TaSe$_{2}$ by minute electron doping provided by substitutional W atoms. We investigate the temperature- and magnetic field-dependence of the superconducting state of Ta$_{1-δ}$W$_δ$Se$_2$ with electron doping ($δ$) using variable temperature (0.34 K - 4.2 K) scanning tunneling spectroscopy (STS). We unveil the emergence of a superconducting dome spanning 0.003 < $δ$ < 0.03 with a maximized critical temperature of 0.9 K, a significant increase from that of bulk TaSe$_{2}$ (T$_C$ = 0.14 K). Superconductivity emerges from an increase of the density of states (DOS) as the Fermi surface approaches a van Hove singularity due to doping. Once the singularity is reached, however, the DOS decreases with $δ$, which gradually weakens the superconducting state, thus shaping the superconducting dome. Lastly, our doping-dependent measurements allow us to unambiguously track the development of a Coulomb glass phase triggered by disorder due to W dopants.
