Research ArticleSUPERCONDUCTIVITY

Inverse correlation between quasiparticle mass and Tc in a cuprate high-Tc superconductor

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Science Advances  18 Mar 2016:
Vol. 2, no. 3, e1501657
DOI: 10.1126/sciadv.1501657
  • Fig. 1 Temperature-dependent magnetoresistance of Y124.

    (A) c-axis resistivity at different temperatures, measured up to μ0H = 67 T. The inset shows the derivative dρc/dH to emphasize the Shubnikov–de Haas QOs. (B) Temperature dependence of the QO amplitude. The red line shows a fit to the Lifshitz-Kosevich expression (see Materials and Methods) giving a quasiparticle mass m* = (1.80 ± 0.05) me (where me is the free electron mass).

  • Fig. 2 Magnetoresistance of Y124 at various pressures at T = 2.5 K.

    Data for p = 0 are shown both before the pressure was applied and after it was removed.

  • Fig. 3 Oscillatory part of resistance versus field for different pressures at T = 2.5 K.

    (A) Three curves for p = 0 GPa. (a) and (b) were measured outside the pressure cell: (a) in a 70-T coil and (b) in the same 60-T coil as the pressure cell measurements. The third curve is the result at p = 0 after depressurizing the cell. The arrows mark the position of a local maximum Bmax in Δρcc. The curves have been offset vertically for clarity. (B) Evolution of the QO frequency with pressure. For p = 0 (before pressurization), the frequency was taken from a direct fit to sin(2πF/B + φ), then the changes in the frequency as p is varied are inferred from Bmax. Similar changes in F were also found by fitting each curve (as for p = 0) but at a higher noise level.

  • Fig. 4 Quasiparticle effective mass in Y124 under hydrostatic pressure.

    (A) Amplitude of QOs as a function of temperature. The curves have been offset vertically for clarity. The solid lines are fits to the Lifshitz-Kosevich formula. The field windows used are given in table S1. (B) Variation of quasiparticle mass with pressure extracted from the fits. The dashed line is a guide to the eye. a.u., arbitrary units.

  • Fig. 5 Quasiparticle mass of Y124 compared to Y123 plotted versus Tc.

    The top scale shows the hole doping level for Y123 (17). Data for Y123 are taken from Ramshaw et al. (15) and the references therein. The dashed line is a guide to the eye.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/2/3/e1501657/DC1

    Fig. S1. Sample dependence of zero-pressure QOs.

    Fig. S2. Effective mass determination at p = 0 for two further samples.

    Fig. S3. Pressure dependence of ρc(T).

    Fig. S4. Comparison of changes in QO frequency between Y123 and Y124.

    Fig. S5. Temperature and pressure dependence of the irreversible field Hirr.

    Table S1. Field windows used for the fitting of temperature-dependent QO amplitudes at various pressures, as shown in Fig. 4.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Sample dependence of zero-pressure QOs.
    • Fig. S2. Effective mass determination at p = 0 for two further samples.
    • Fig. S3. Pressure dependence of ρc(T).
    • Fig. S4. Comparison of changes in QO frequency between Y123 and Y124.
    • Fig. S5. Temperature and pressure dependence of the irreversible field Hirr.
    • Table S1. Field windows used for the fitting of temperature-dependent QO amplitudes at various pressures, as shown in Fig. 4.

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