Abstract
Layered transition-metal dichalcogenides that host coexisting charge-density wave (CDW) and superconducting orders provide ideal systems for exploring the effects of dimensionality on correlated electronic phases. Dimensionality has a profound effect on both superconductivity and CDW instabilities. Here we report a substantial enhancement of the superconducting to 3.4 K for in the monolayer limit, compared to 0.8 K in the bulk. In addition, the transport signature of a CDW phase transition vanishes in the two-dimensional limit. In our analysis of electronic and vibrational properties of this material, we show that a reduction of the CDW amplitude results in a substantial increase of the density of states at the Fermi energy, which can boost by an amount similar to that seen in experiment. Our results indicate competition between CDW order and superconductivity in ultrathin down to the monolayer limit, providing insight toward understanding correlated electronic phases in reduced dimensions.
- Received 26 October 2017
- Revised 18 June 2018
DOI:https://doi.org/10.1103/PhysRevB.98.035203
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