An explanation for pressure-induced superconductivity in WB<sub>2</sub>

ORAL

Abstract

Our recent experimental investigations into the hP12 phase of WB2 revealed that WB2 superconducts above 50GPa with a maximum superconducting critical temperature Tc of 17 K at 90 GPa. High-pressure resistivity and XRD measurement revealed no structural phase transition. Calculated electron-phonon Tc for the hP12 phase fails to explain the observed superconductivity. In this talk, we present theoretical evidence that the formation of planar defects at high pressure explains the observed superconductivity. Enthalpy calculations indicate that stacking faults and twin boundaries can form during plastic deformation of the hP12 WB2 phase at high pressure. Furthermore, the atomic arrangement at these planar defects resembles the arrangement of atoms in the MgB2 P6/mmm structure. Our electron-phonon coupling calculations show that P6/mmm WB2 has the highest Tc among the competing phases and this phase is thermodynamically stable above 130GPa. The formation of planar defects is also consistent with the observed change in c/a ratio above about 50 GPa. Thus, the formation and percolation of mechanically induced stacking faults and twin boundaries lead to filamentary superconductivity in WB2 at high pressure. Our results may lead to an alternate route for designing superconducting materials.

*Work on this project was supported by the US Department of Energy Basic Energy Sciences under Contract No. DE-SC-0020385. High-pressure equipment development at UF supported by DMR-1453752. HPXRD at the Advanced Photon Source was supported by the U.S. Department of Energy (DOE) National Nuclear Security Administration (NNSA) through the Chicago/DOE Alliance Center (CDAC). A.H. acknowledges the support from the Center for Bright Beams, U.S. National Science Foundation award PHY-1549132.

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Publication: [1] arXiv:2109.11521 [cond-mat.supr-con]. https://arxiv.org/abs/2109.11521

Presenters

  • Ajinkya C Hire

    • Department of Materials Science and Engineering, University of Florida
    • University of Florida

Authors

  • Ajinkya C Hire

    • Department of Materials Science and Engineering, University of Florida
    • University of Florida

  • Jinhyuk Lim

    • Department of Physics, University of Florida
    • University of Florida

  • Yundi Quan

    • Department of Physics, University of Florida
    • University of Florida

  • JungSoo Kim

    • Department of Physics, University of Florida
    • University of Florida

  • Stephen R Xie

    • Department of Materials Science and Engineering, University of Florida
    • KBR Inc., Intelligent Systems Division, NASA Ames Research Center
    • University of Florida

  • Ravhi S Kumar

    • University of Illinois at Chicago
    • Department of Physics, University of Illinois at Chicago
    • University of Illinois Chicago

  • Dmitry Popov

    • HPCAT, X-ray Science Division, Argonne National Laboratory
    • High-pressure Collaborative Access Team, Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439
    • Argonne National Laboratory

  • Changyong Park

    • HPCAT, X-ray Science Division, Argonne National Laboratory
    • Argonne National Laboratory

  • Russell J Hemley

    • University of Illinois Chicago
    • University of Illinois at Chicago
    • George Washington Univ
    • Departments of Physics and Chemistry, University of Illinois at Chicago
    • Department of Physics, University of Illinois at Chicago, Chicago, IL 60607, USA; Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
    • Department of Physics, University of Illinois Chicago, Chicago, USA
    • University of Illinois at Chicago, USA

  • James J Hamlin

    • University of Florida
    • Department of Physics, University of Florida

  • Richard G. G Hennig

    • University of Florida
    • Department of Materials Science and Engineering, University of Florida
    • Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, United States

  • Peter J Hirschfeld

    • University of Florida
    • Department of Physics, University of Florida

  • Gregory R Stewart

    • Department of Physics, University of Florida
    • University of Florida