Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                

Superconductivity and equation of state of lanthanum at megabar pressures

Wuhao Chen, Dmitrii V. Semenok, Ivan A. Troyan, Anna G. Ivanova, Xiaoli Huang, Artem R. Oganov, and Tian Cui
Phys. Rev. B 102, 134510 – Published 26 October 2020
PDFHTMLExport Citation
Abstract
Authors
Article Text
  • INTRODUCTION
  • EXPERIMENTAL AND THEORETICAL METHODS
  • RESULTS AND DISCUSSION
  • CONCLUSIONS
  • ACKNOWLEDGMENTS
    • Supplemental Material
    References

    Abstract

    Lanthanum (La) is the first member of the lanthanoid that has recently raised considerable interest because of its unique La superhydride LaH10 and its own superconducting properties. There has been a lack of experimental evidence for the equation of state (EOS) and superconductivity of La at pressures exceeding one megabar. Here, we extend the pressure range up to 140 GPa to explore the EOS and superconductivity of La via the electrical resistance and x-ray diffraction measurements. We identified the phase transition sequences by the La Bail refinements of the experimental XRD patterns and discovered a distorted fcc-La phase (space group Fmmm) above 78 GPa with nonhydrostatic pressure transmitting media. All the experimental pressure-volume data were fitted by the third-order Birch-Murnaghan equation: V0=37.5Å3, B0=14.5(1)GPa, and B0′=5. Superconductivity still existed in the distorted fcc-La with an onset critical temperature Tc of 9.6 K at 78 GPa, which decreases to 2.2 K at 140 GPa. We calculated the superconducting parameters of La at several pressure points, and discussed the difference from experimetal Tc.

    • Figure
    • Figure
    • Figure
    • Figure
    • Received 6 March 2019
    • Revised 13 June 2020
    • Accepted 24 August 2020

    DOI:https://doi.org/10.1103/PhysRevB.102.134510

    ©2020 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    Equations of statePressure effectsSuperconducting phase transitionSuperconductors
    Condensed Matter, Materials & Applied Physics

    Authors & Affiliations

    Wuhao Chen1, Dmitrii V. Semenok2, Ivan A. Troyan3, Anna G. Ivanova3, Xiaoli Huang1,*, Artem R. Oganov2, and Tian Cui4,1,†

    • 1State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
    • 2Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel Street, Moscow 143026, Russia
    • 3Shubnikov Institute of Crystallography, Federal Scientific Research Center Crystallography and Photonics, Russian Academy of Sciences, Moscow 119333, 59 Leninskii Prospect, Russia
    • 4School of Physical Science and Technology, Ningbo University, Ningbo 315211, China

    • *Corresponding author: huangxiaoli@jlu.edu.cn
    • †Corresponding author: cuitian@jlu.edu.cn

    Article Text (Subscription Required)

    Click to Expand

    Supplemental Material (Subscription Required)

    Click to Expand

    References (Subscription Required)

    Click to Expand
    Issue

    Vol. 102, Iss. 13 — 1 October 2020

    Reuse & Permissions
    Access Options
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1

      (a), (b) Rietveld refinement of the experimental XRD pattern of La sample for two experimental runs. Positions of the Bragg reflections from La, MgO, and W gasket are marked with black, yellow, and blue vertical ticks, respectively. (c) The lattice parameters as a function of pressure. The straight dashed lines represent the phase boundaries. (d) Pressure-volume relations for La sample. The gray solid curve shows the third-order Birch-Murnaghan equation fitting to the experimental data (squares and circles). Triangles and cyan dashed curve represent the data from Ref. [20].

      Reuse & Permissions
    • Figure 2
      Figure 2

      (a) Schematic of the assembly used for the electrical resistance measurements. The sample chamber consisted of a tungsten outer gasket (W) with an insulating Al2O3 and epoxy. (b) Microphotograph of a sample at 140 GPa illuminated from the top. An inset shows the sample illuminated from the bottom.

      Reuse & Permissions
    • Figure 3
      Figure 3

      (a) Resistance of the La sample as a function of temperature at various pressures during cooling in the experimental run 1. The gray characters represent the magnification of R. The lines with arrows show the definition of the superconducting transition temperature Tc. (b) The phase diagram and superconducting transition temperature Tc of La as a function of pressure. The red hexagon, green triangle, and blue pentagon symbols denote our experimental superconducting Tc data from runs 1–3. The purple asterisks and gray squares represent the data from Wittig et al. [15] and Tissen et al. [18]. The black dashed line marks the phase-transition boundaries determined by the present study.

      Reuse & Permissions
    • Figure 4
      Figure 4

      (a) The experimentally measured superconducting transition of the La sample at 140 GPa with a magnetic field applied. In the inset, the dots show the measured values of Tc and magnetic field, while the solid lines represent fittings by the WHH and LG equations. (b), (c) The calculated superconducting parameters of the distorted fcc-La phase at 100 and 130 GPa.

      Reuse & Permissions
    ×

    Sign up to receive regular email alerts from Physical Review B

    Log In

    Cancel
    ×

    Search

    Article Lookup

    Paste a citation or DOI
    Enter a citation
    ×