Magnetization and transport properties in the superconducting Pr2Ba4Cu7O15−δ with metallic double-chain

Abstract

We have reported the effect of pressure on the magnetization, and transport properties in the nominal composition Pr2Ba4Cu7O 15−δ synthesized by a sol-gel technique. A reduction treatment of the as-sintered sample in vacuum causes higher superconductivity achieving Tc,on =∼ 30 K for δ = 0.94. Application of hydrostatic pressure on the oxygen depleted sample enhances its onset temperature up to 36 K at 1.2 GPa, indicating the nearly optimum doping level of the charge carrier in comparison to the pressure dependence of lower Tc samples with δ = 0.45. Seebeck coefficient of the superconducting sample shows a metallic conduction, followed by a clear drop below Tc,on and is in its temperature dependence below 100 K quite different from that of the non-superconducting one. This finding strongly suggests a dramatic change of the electronic state along the CuO double chain due to the reduction treatment for the appearance of superconductivity .

Effect of Magnetic Field on the Superconducting Phase in the Electron-Doped Metallic Double-Chain Compound Pr2Ba4Cu7O15-δ

“…7 temperature dependence of Seebeck coefficient S(T ) of the polycrystalline Pr 2 Ba 4 Cu 7 O 15−δ , to examine some differences in the electronic state between the reduced and as-sintered samples. We note that the S behavior of both as-sintered and reduced samples prepared by a sol-gel method 13 is, in its magnitude and temperature dependence, very similar to the present data. Upon decreasing temperature, the value of S of the superconducting sample reaches a broad maximum around ∼230 K, then shows a rapid decrease below 200 K, and finally follows a substantial drop associated with the superconducting transition at low temperatures below T on c = 26.5K.…”

“…Polycrystalline samples of Pr 2 Ba 4 Cu 7 O 15−δ (Pr247) were synthesized using citrate pyrolysis and sol-gel methods. 13,19 After several annealing processes, resultant precursors were pressed into a pellet and it was then calcined at 875∼887 • C for a long time over 120-180 h under ambient oxygen pressure. The reduction treatment on its as-sintered sample in vacuum at 500 • C for 48 h yields oxygen removal, resulting in a realization of the superconductivity.…”

“…11 Recently, Toshima et al, reported the effect of pressure on the magnetization, and transport properties in the nominal composition Pr 2 Ba 4 Cu 7 O 15−δ synthesized by a sol-gel technique. 13 Their work reveals that the higher superconductivity of T on c =∼ 30 K for the δ = 0.94 sample is achieved and is enhanced up to 36 K under the applied pressure of 1.2 GPa. From the theoretical point of view, the superconductivity of Pr247 was clarified by using the CuO double chain model.…”