Superconductivity in rubidium-substituted Ba1−xRbxTi2Sb2O

Abstract

We report on the synthesis and the physical properties of Ba1−xRbxTi2Sb2O (x≤0.4) by x-ray diffraction, superconducting quantum interference device magnetometry, resistivity, and specific-heat measurements. Upon hole doping by substituting Ba with Rb, we find superconductivity with a maximum Tc=5.4 K. Simultaneously, the charge-density-wave transition temperature is strongly reduced from TCDW≈55 K in the parent compound BaTi2Sb2O and seems to be suppressed for x≥0.2. The bulk character of the superconducting state for the optimally doped sample (x=0.2) is confirmed by the occurrence of a well developed discontinuity in the specific heat at Tc, with ΔC/Tc≈22 mJ/mol K2, as well as a large Meissner-shielding fraction of ≈40%. The isotropically averaged lower and upper critical fields of the optimally doped sample (x=0.2) are estimated to μ0Hc,1(0)≈3.8 mT and μ0Hc,2(0)≈2.3 T, respectively, indicating that these compounds are strongly type-II superconductors.

Source-reported materials — not catalogue approval

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