Carrier Transport Enhancement by Doping Rubidium in Cu 0.5 Tl 0.5 -1223 Superconducting Phase

The doping of alkali metals in the charge reservoir layer of copper thallium-based superconductors was of keen interest to the scientific community. To better understand how charge carriers influence superconductivity, we synthesize Cu 0.5 Tl 0.5 Ba 2 Ca 2 Cu 3− y Rb y O 10− δ ( y = 0, 1.0, 2, 2.5, 3) compounds by solid-state reaction technique. Utilizing x-ray diffraction, x-ray fluorescence spectroscopy, scanning electron microscopy, temperature-dependent resistivity, and Fourier transform infrared absorption measurements, we have studied the effects of rubidium Rb(5s 1 ) substitution on the Cu 0.5 Tl 0.5 -1223 crystal structure. Although the sample mainly comprises tetragonal-1223 phase, some nominal derivative phases of RbO 2 have also been identified. As the concentration of the Rb(5s 1 ) in CuO 2 superconducting plane increases, the critical temperature ( T c ) decreases until the final compound has no superconductivity. The electronic response of charge carriers and lattice vibrations is present in the FTIR spectra of samples. The fluctuation-induced conductivity analysis was used to extract the intrinsic microscopic superconducting parameters, including the cross-over temperatures, coherence length along the c -axis ξ c(0) , inter-layer coupling ( J ), and Fermi velocity ( V F ). Enhancement in carrier density within Rb/CuO 2 planes leads to suppression in T c , suggesting that an-harmonic oscillations were produced in the conducting Rb/CuO 2 planes as a result of the heavy mass of 37 Rb 85 compared to 29 Cu 63 .