Title: Proximity-Induced Superconductivity in Monolayer MoS₂

Abstract

Proximity effects in superconducting normal (SN) material heterostructures with metals and semiconductors have long been observed and theoretically described in terms of Cooper pair wave functions and Andreev reflections. Whereas the semiconducting N-layer materials in the proximity experiments to date have been doped and tens of nanometers thick, we present here a proximity tunneling study involving a pristine single-layer transition-metal dichalcogenide film of MoS2 placed on top of a Pb thin film. Scanning tunneling microscopy and spectroscopy experiments together with parallel theoretical analysis based on electronic structure calculations and Green’s function modeling allow us to unveil a two-step process in which MoS2 first becomes metallic and then is induced into becoming a conventional s-wave Bardeen–Cooper–Schrieffer-type superconductor. The lattice mismatch between the MoS2 overlayer and the Pb substrate is found to give rise to a topographic moiré pattern. Even though the induced gap appears uniform in location, the coherence peak height of the tunneling spectra is modulated spatially into a moiré pattern that is similar to but shifted with respect to the moiré pattern observed in topography. The aforementioned modulation is shown to originate from the atomic-scale structure of the SN interface and the nature of local atomic orbitals that aremore » involved in generating the local pairing potential. Our study indicates that the local modulation of induced superconductivity in MoS2 could be controlled via geometrical tuning, and it thus shows promise toward the integration of monolayer superconductors into next-generation functional electronic devices by exploiting proximity-effect control of quantum phases.« less

Authors:

Trainer, Daniel J. ^[1]; Wang, BaoKai ^[2]; Bobba, Fabrizio ^[3]; Samuelson, Noah ^[4]; Xi, Xiaoxing ^[1]; Zasadzinski, John ^[4]; Nieminen, Jouko  ^[5];

• Search DOE PAGES for author "Nieminen, Jouko"
• Search DOE PAGES for ORCID "0000-0003-0817-1448"

Bansil, Arun ^[2]; Iavarone, Maria  ^[1]

• Search DOE PAGES for author "Iavarone, Maria"
• Search DOE PAGES for ORCID "0000-0002-9631-9184"

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+ Show Author Affiliations

1. Temple Univ., Philadelphia, PA (United States)
2. Northeastern Univ., Boston, MA (United States)
3. Univ. of Salemo, Fisciano (Italy); Temple Univ., Philadelphia, PA (United States)
4. Illinois Inst. of Technology, Chicago, IL (United States)
5. Northeastern Univ., Boston, MA (United States); Tampere Univ. of Technology (Finland)

Publication Date:

Mon Jan 13 00:00:00 EST 2020

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Complex Materials from First Principles (CCM); Temple Univ., Philadelphia, PA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1608034

Alternate Identifier(s):

OSTI ID: 1734988

Grant/Contract Number:  

SC0004556; SC0012575; FG02-07ER46352; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

ACS Nano

Additional Journal Information:

Journal Volume: 14; Journal Issue: 3; Related Information: https://pubs.acs.org/doi/suppl/10.1021/acsnano.9b07475/suppl_file/nn9b07475_si_001.pdf; Journal ID: ISSN 1936-0851

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; molybdenum disulfide; monolayer; superconductivity; proximity effect; STM; molybdenum disulfide monolayer superconductivity proximity effect STM