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Title: Superconducting order from disorder in 2H-TaSe 2-xS x

Abstract

Here, we report on the emergence of robust superconducting order in single crystal alloys of TaSe 2$ -$x S x (0 ≤ × ≤2). The critical temperature of the alloy is surprisingly higher than that of the two end compounds TaSe2 and TaS2. The evolution of superconducting critical temperature T c(x) correlates with the full width at half maximum of the Bragg peaks and with the linear term of the high-temperature resistivity. The conductivity of the crystals near the middle of the alloy series is higher or similar than that of either one of the end members 2H-TaSe 2 and/or 2H-TaS 2. It is known that in these materials superconductivity is in close competition with charge density wave order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the charge density wave order.

Authors:
 [1];  [2];  [3];  [3];  [4];  [4];  [5];  [3];  [6];  [3];  [7];  [8];  [3];  [9];  [3]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.; Chinese Academy of Sciences (CAS), Hefei (China). Key Lab. of Materials Physics, Inst. of Solid State Physics
  2. Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics & Astronomy
  3. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.
  4. Brookhaven National Lab. (BNL), Upton, NY (United States)
  5. Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics
  6. Brookhaven National Lab. (BNL), Upton, NY (United States). Instrumentation Division
  7. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.; Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics
  8. Chinese Academy of Sciences (CAS), Hefei (China). Key Lab. of Materials Physics, Inst. of Solid State Physics; Chinese Academy of Sciences (CAS), Beijing (China). High Magnetic Field Lab.
  9. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.; Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics & Astronomy
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1351729
Report Number(s):
BNL-113715-2017-JA
Journal ID: ISSN 2397-4648
Grant/Contract Number:
SC0012704; 11404342
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
npj Quantum Materials
Additional Journal Information:
Journal Volume: 2; Journal Issue: 1; Journal ID: ISSN 2397-4648
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE

Citation Formats

Li, Lijun, Deng, Xiaoyu, Wang, Zhen, Liu, Yu, Abeykoon, Milinda, Dooryhee, Eric, Tomic, Aleksandra, Huang, Yanan, Warren, John B., Bozin, Emil S., Billinge, Simon J. L., Sun, Yuping, Zhu, Yimei, Kotliar, Gabriel, and Petrovic, Cedomir. Superconducting order from disorder in 2H-TaSe2-xSx. United States: N. p., 2017. Web. doi:10.1038/s41535-017-0016-9.
Li, Lijun, Deng, Xiaoyu, Wang, Zhen, Liu, Yu, Abeykoon, Milinda, Dooryhee, Eric, Tomic, Aleksandra, Huang, Yanan, Warren, John B., Bozin, Emil S., Billinge, Simon J. L., Sun, Yuping, Zhu, Yimei, Kotliar, Gabriel, & Petrovic, Cedomir. Superconducting order from disorder in 2H-TaSe2-xSx. United States. doi:10.1038/s41535-017-0016-9.
Li, Lijun, Deng, Xiaoyu, Wang, Zhen, Liu, Yu, Abeykoon, Milinda, Dooryhee, Eric, Tomic, Aleksandra, Huang, Yanan, Warren, John B., Bozin, Emil S., Billinge, Simon J. L., Sun, Yuping, Zhu, Yimei, Kotliar, Gabriel, and Petrovic, Cedomir. Fri . "Superconducting order from disorder in 2H-TaSe2-xSx". United States. doi:10.1038/s41535-017-0016-9. https://www.osti.gov/servlets/purl/1351729.
@article{osti_1351729,
title = {Superconducting order from disorder in 2H-TaSe2-xSx},
author = {Li, Lijun and Deng, Xiaoyu and Wang, Zhen and Liu, Yu and Abeykoon, Milinda and Dooryhee, Eric and Tomic, Aleksandra and Huang, Yanan and Warren, John B. and Bozin, Emil S. and Billinge, Simon J. L. and Sun, Yuping and Zhu, Yimei and Kotliar, Gabriel and Petrovic, Cedomir},
abstractNote = {Here, we report on the emergence of robust superconducting order in single crystal alloys of TaSe2$ -$x Sx (0 ≤ × ≤2). The critical temperature of the alloy is surprisingly higher than that of the two end compounds TaSe2 and TaS2. The evolution of superconducting critical temperature Tc(x) correlates with the full width at half maximum of the Bragg peaks and with the linear term of the high-temperature resistivity. The conductivity of the crystals near the middle of the alloy series is higher or similar than that of either one of the end members 2H-TaSe2 and/or 2H-TaS2. It is known that in these materials superconductivity is in close competition with charge density wave order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the charge density wave order.},
doi = {10.1038/s41535-017-0016-9},
journal = {npj Quantum Materials},
number = 1,
volume = 2,
place = {United States},
year = {Fri Feb 24 00:00:00 EST 2017},
month = {Fri Feb 24 00:00:00 EST 2017}
}

Journal Article:
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  • Superconducting T/sub c/ can be increased by a low concentration, less than 1%, of irradiation-induced defects in the layered charge-density-wave (CDW) compounds 2H-NbSe/sub 2/, 2H-TaS/sub 2/, and 2H-TaSe/sub 2/. This is due to the pinning effect of the defects which perturbs the long-range coherence of the CDW. Resistive transitions show tails below a first drop, suggesting inhomogeneous superconductivity. Such effects are proposed to be related to CDW domains.
  • The intercalation of Fe into the van der Waals gap in the 2H phase transition-metal dichalcogenides NbSe[sub 2], TaSe[sub 2], and TaS[sub 2] produces many interesting electronic, magnetic, and structural effects. The scanning tunneling microscope (STM) and atomic force microscope (AFM) prove to be very sensitive to these changes and we report a wide range of results as a function of Fe concentration. All three materials support similar 3[bold a][sub 0][times]3[bold a][sub 0] charge-density-wave (CDW) structures in the pure state at low temperatures. At low concentrations of Fe the CDW superlattice is still strong at 4.2 K and persists tomore » high concentrations of Fe. At high concentrations, the Fe becomes ordered in the octahedral holes in the van der Waals gaps, and superlattices of the form 2[bold a][sub 0][times]2[bold a][sub 0] and [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] are observed. These can be detected at both 300 and 4.2 K. STM spectroscopy at 4.2 K shows that in 2H-Fe[sub [ital x]]NbSe[sub 2] and 2H-Fe[sub [ital x]]TaSe[sub 2] the energy gap in the electronic spectrum is initially reduced, but stabilizes at higher Fe concentrations and remains well defined for the ordered 2[bold a][sub 0][times]2[bold a][sub 0] phase. A transition from a CDW to a mixed CDW and spin-density-wave state is indicated, since these high Fe concentration phases are antiferromagnetic. In 2H-Fe[sub [ital x]]TaS[sub 2] both 2[bold a][sub 0][times]2[bold a][sub 0] and [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] superlattices are observed. The 2[bold a][sub 0][times]2[bold a][sub 0] regions show a large energy gap, while the [radical]3 [bold a][sub 0][times] [radical]3 [bold a][sub 0] do not. The latter phase is ferromagnetic and would not be expected to exhibit a gap.« less
  • We report high-resolution synchrotron x-ray-scattering measurements on two compounds with charge-density-wave (CDW) phase transitions, 2H-TaSe/sub 2/ and NbSe/sub 3/. In these materials the scattering from the CDW superlattice is typically more than 3 orders of magnitude smaller than that of the host lattice. The increased flux available with a synchrotron source allows one to study weak CDW scattering with a Q resolution on the order of 10/sup -4/ A/sup -1/, which is 1 to 2 orders of magnitude better than that attainable with a rotating-anode source. In the case of 2H-TaSe/sub 2/, we were able to measure finite widths ofmore » the CDW superlattice peaks and to determine precisely the temperature dependence of the CDW incommensurability near the commensurate-incommensurate transition. We have established a lower bound for the CDW coherence length in NbSe/sub 3/, and we have shown that the sum of the two CDW wave vectors is not commensurate as previously suspected. We have also looked with higher precision for possible effects of the electric field on the CDW structure in NbSe/sub 3/.« less
  • Detailed measurements of the specific heat and resistivity have been made on samples of 2H-TaSe/sub 2/ and 2H-TaS/sub 2/ near their charge-density-wave phase transitions. Because the crystal quality of 2H-TaSe/sub 2/ is much better than that of 2H-TaS/sub 2/, we emphasize the results on 2H-TaSe/sub 2/ and make quantitative comparison with the theory of charge-density waves in this material. In 2H-TaSe/sub 2/ the normal to incommensurate phase transition was found to be second order; the incommensurate to commensurate transition was first order. Specific-heat measurements on this material indicate that the zero-temperature coherence length is relatively short; ..pi..xi/sub 0/ approx. =more » 14 A. The resistivity of 2H-TaSe/sub 2/ immediately above the normal to incommensurate phase transition is dominated by resistive scattering from the periodic structural deformations accompanying the charge-density waves. The specific-heat and resistivity measurements both indicate that the normal to incommensurate phase transition in 2H-TaSe/sub 2/ can be analyzed within a nearly-mean-field model.« less