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Title: Selenium capped monolayer NbSe 2 for two-dimensional superconductivity studies

Abstract

Superconductivity in monolayer niobium diselenide (NbSe 2) on bilayer graphene is studied by electrical transport. Monolayer NbSe 2 is grown on bilayer graphene by molecular beam epitaxy and capped with a selenium film to avoid degradation in air. The selenium capped samples have T C = 1.9 K. In situ measurements down to 4 K in ultrahigh vacuum show that the effect of the selenium layer on the transport is negligible. Lastly, the superconducting transition and upper critical fields in air exposed and selenium capped samples are compared. Schematic of monolayer NbSe 2/bilayer graphene with selenium capping layer and electrical contacts.

Authors:
 [1];  [2];  [3];  [2];  [2];  [4];  [4];  [4];  [5];  [6];  [6]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
  2. Univ. of California, Berkeley, CA (United States). Dept. of Physics
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Institute for Materials and Energy Science (SIMES); Stanford Univ., CA (United States). Geballe Lab. for Advanced Materials, Dept. of Physics and Applied Physics
  6. Univ. of California, Berkeley, CA (United States). Dept. of Physics; Univ. of California, Berkeley, CA (United States). Kavli Energy NanoSciences Inst.; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1398445
Grant/Contract Number:
AC02-05CH11231; EFRI-2DARE 1542741; DMR-1206512
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physica Status Solidi B. Basic Solid State Physics
Additional Journal Information:
Journal Volume: 253; Journal Issue: 12; Journal ID: ISSN 0370-1972
Publisher:
Wiley-Blackwell
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; monolayer niobium diselenide; superconductivity; molecular beam epitaxy; in situ

Citation Formats

Onishi, Seita, Ugeda, Miguel M., Zhang, Yi, Chen, Yi, Ojeda-Aristizabal, Claudia, Ryu, Hyejin, Mo, Sung-Kwan, Hussain, Zahid, Shen, Zhi-Xun, Crommie, Michael F., and Zettl, Alex. Selenium capped monolayer NbSe2 for two-dimensional superconductivity studies. United States: N. p., 2016. Web. doi:10.1002/pssb.201600235.
Onishi, Seita, Ugeda, Miguel M., Zhang, Yi, Chen, Yi, Ojeda-Aristizabal, Claudia, Ryu, Hyejin, Mo, Sung-Kwan, Hussain, Zahid, Shen, Zhi-Xun, Crommie, Michael F., & Zettl, Alex. Selenium capped monolayer NbSe2 for two-dimensional superconductivity studies. United States. doi:10.1002/pssb.201600235.
Onishi, Seita, Ugeda, Miguel M., Zhang, Yi, Chen, Yi, Ojeda-Aristizabal, Claudia, Ryu, Hyejin, Mo, Sung-Kwan, Hussain, Zahid, Shen, Zhi-Xun, Crommie, Michael F., and Zettl, Alex. Mon . "Selenium capped monolayer NbSe2 for two-dimensional superconductivity studies". United States. doi:10.1002/pssb.201600235. https://www.osti.gov/servlets/purl/1398445.
@article{osti_1398445,
title = {Selenium capped monolayer NbSe2 for two-dimensional superconductivity studies},
author = {Onishi, Seita and Ugeda, Miguel M. and Zhang, Yi and Chen, Yi and Ojeda-Aristizabal, Claudia and Ryu, Hyejin and Mo, Sung-Kwan and Hussain, Zahid and Shen, Zhi-Xun and Crommie, Michael F. and Zettl, Alex},
abstractNote = {Superconductivity in monolayer niobium diselenide (NbSe2) on bilayer graphene is studied by electrical transport. Monolayer NbSe2 is grown on bilayer graphene by molecular beam epitaxy and capped with a selenium film to avoid degradation in air. The selenium capped samples have TC = 1.9 K. In situ measurements down to 4 K in ultrahigh vacuum show that the effect of the selenium layer on the transport is negligible. Lastly, the superconducting transition and upper critical fields in air exposed and selenium capped samples are compared. Schematic of monolayer NbSe2/bilayer graphene with selenium capping layer and electrical contacts.},
doi = {10.1002/pssb.201600235},
journal = {Physica Status Solidi B. Basic Solid State Physics},
number = 12,
volume = 253,
place = {United States},
year = {Mon Aug 01 00:00:00 EDT 2016},
month = {Mon Aug 01 00:00:00 EDT 2016}
}

Journal Article:
Free Publicly Available Full Text
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Cited by: 2works
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  • We report modulation of the superconducting critical temperature (T{sub c}) of ultrathin niobium diselenide (NbSe{sub 2}) single crystals by gating an electric double-layer transistor. We realized reversible and irreversible changes of the T{sub c} by adjusting the operating range of the voltage. The reversible and irreversible responses correspond to the electrostatic carrier doping and the electrochemical etching of the crystal, respectively. The results suggest that electric double-layer gating provides opportunities to control and functionalize collective electronic phenomena in two-dimensional crystals.
  • We investigate the effect of individual atomic impurities on the superconducting state that they are embedded in. Using low temperature scanning tunneling microscopy and spectroscopy we could identify Co and Mn atoms in the Co{sub x}NbSe{sub 2} and Mn{sub x}NbSe{sub 2} single crystals and observe the influence on the local electronic density of states (LDOS) at 0.4 K. We find that Co is in the weak scattering limit. In this case the LDOS is quite homogeneous on the sample surface, despite the number of defects, and retains sharp coherent superconducting peaks. This is in strong contrast to the effects ofmore » Mn impurities, which locally destroy superconductivity. In this case the LDOS shows a strong enhancement of spectral weight inside the superconducting gap even far from the Mn atoms. Moreover, two impurity bound states are found within the superconducting gap at E/{Delta}{sub 0} = 0.18 and 0.36 at locations close to defects.« less
  • The /sup 93/Nb nuclear-quadrupole-resonance frequencies have been measured as a function of temperature in 2H-NbSe/sub 2/ between 38 and 376 K. A nearly linear behavior ..nu../sub Q/=a-bT is observed between 77 and 376 K in contrast to an approximate ..nu../sub Q/(0)(1-..cap alpha..T/sup 3///sup 2/) dependence found in most noncubic metals over the same temperature range. Using a variation of Jena's theoretical treatment of the temperature dependence of ..nu../sub Q/ in noncubic metals, with the consideration that NbSe/sub 2/ is a quasi-two-dimensional structure, we present an explanation of the nearly linear dependence of ..nu../sub Q/ on T in NbSe/sub 2/. (AIP)
  • Results of atomic force microscope (AFM) and scanning tunneling microscope (STM) studies of superlattices and long-range modulations induced by impurities in transition metal chalcogenides are presented. Superlattices formed by Fe intercalation into the van der Waals gaps of 2H--NbSe[sub 2], 2H--TaSe[sub 2] and 2H--TaS[sub 2] show ordered occupation of the octahedral holes and STM spectroscopy shows density-wave energy gaps existing in the antiferromagnetic phases. In NbSe[sub 3], interstitial impurities such as Fe, Co, Cr, and V induce long-range modulated structures that can be detected at room temperature with AFM scans. These modulations modify the charge-density wave structure forming at lowmore » temperature and STM spectroscopy has been used to measure these changes.« less