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 Tc to 3.4 K for 2H-TaS2 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 Tc by an amount similar to that seen in experiment. Our results indicate competition between CDW order and superconductivity in ultrathin 2H-TaS2 down to the monolayer limit, providing insight toward understanding correlated electronic phases in reduced dimensions.
| Original language | English |
|---|---|
| Article number | 035203 |
| Journal | Physical Review B |
| Volume | 98 |
| Issue number | 3 |
| DOIs | |
| State | Published - 20 Jul 2018 |
| Externally published | Yes |
Bibliographical note
Funding Information:This work has been primarily supported by the U.S. DOE, BES Office, Division of Materials Sciences and Engineering under Award No. DE-SC0001819 (Y.Y. and P.J.-H.) and by the Gordon and Betty Moore Foundations EPiQS Initiative through Grant No. GBMF4541 to P.J.-H. Fabrication work (E.N.-M.) and theory analysis were partly supported by the NSF-STC Center for Integrated Quantum Materials under Award No. DMR-1231319 (V.F., S.F.) and ARO MURI Award No. W911NF-14-0247 (E.K.). This work made use of the MRSEC Shared Experimental Facilities at MIT, supported by the National Science Foundation under Award No. DMR-14-19807 and of Harvard CNS, supported by NSF ECCS under Award No. 1541959. S.F. used Odyssey cluster of the FAS by the Research Computing Group at Harvard University, and the Extreme Science and Engineering Discovery Environment, which is supported by NSF Grant No. ACI-1053575. J.R. acknowledges the Gordon and Betty Moore Foundation under the EPiQS initiative under Grant No. GBMF4303. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by NSF Cooperative Agreement No. DMR-1157490 and the State of Florida. Growth of hexagonal boron nitride crystals was supported by the Elemental Strategy Initiative conducted by the MEXT, Japan and JSPS KAKENHI Grants No. JP15K21722 and No. JP25106006.
Funding Information:
We thank Yuan Cao, Jason Luo, and Jiarui Li for experimental help. We also thank Patrick A. Lee, Dennis Huang, Miguel A. Cazalilla, and Bertrand I. Halperin for fruitful discussions. This work has been primarily supported by the U.S. DOE, BES Office, Division of Materials Sciences and Engineering under Award No. DE-SC0001819 (Y.Y. and P.J.-H.) and by the Gordon and Betty Moore Foundations EPiQS Initiative through Grant No. GBMF4541 to P.J.-H. Fabrication work (E.N.-M.) and theory analysis were partly supported by the NSF-STC Center for Integrated Quantum Materials under Award No. DMR-1231319 (V.F., S.F.) and ARO MURI Award No. W911NF-14-0247 (E.K.). This work made use of the MRSEC Shared Experimental Facilities at MIT, supported by the National Science Foundation under Award No. DMR-14-19807 and of Harvard CNS, supported by NSF ECCS under Award No. 1541959. S.F. used Odyssey cluster of the FAS by the Research Computing Group at Harvard University, and the Extreme Science and Engineering Discovery Environment, which is supported by NSF Grant No. ACI-1053575. J.R. acknowledges the Gordon and Betty Moore Foundation under the EPiQS initiative under Grant No. GBMF4303. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by NSF Cooperative Agreement No. DMR-1157490 and the State of Florida. Growth of hexagonal boron nitride crystals was supported by the Elemental Strategy Initiative conducted by the MEXT, Japan and JSPS KAKENHI Grants No. JP15K21722 and No. JP25106006.
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