Abstract
本文工作為量測摻鐠(Pr)之(R1-xPrx)Ba2Cu3O7及缺氧樣品包括RBa2Cu3O6+x(R = Yb, Er, Y, Ho, Dy, Gd, Eu, Sm, Nd)、(Y0.8Gd0.2)Ba2Cu3O6+x、 YBa2(Cu0.98Ni0.02)3O6+x 及(R0.85Pr0.15)Ba2Cu3O6+x(R =Y, Gd)等超導樣品之自旋能隙溫度(spin gap temperature, Ts)。定性地分析以上所列樣品的超導轉變溫度(Tc)及自旋能隙溫度(Ts)之間的關係，希望能藉以探討"自旋能隙"(spin gap)之機制。 在缺氧且無摻雜的樣品中，經比較各種稀土元素所構成的RBCO之超導轉變溫度與自旋能隙溫度的關係，發現R位置上的稀土元素並不影響自旋能隙溫度，而在摻鐠且全氧的RBCO中，當鐠的含量相同時，發現自旋能隙溫度隨R位置上稀土元素的離子半徑增大而提高。 擇定一稀土元素，比較其缺氧與摻鐠RBCO樣品的超導轉變溫度與自旋能隙溫度的關係，發現鐠雖然會使載流子濃度降低而導致自旋能隙發生，但同時也會抑制自旋能隙溫度。 進一步比較摻鐠與摻鎳(Ni)且缺氧之YBCO的超導轉變溫度與自旋能隙溫度的關係，發現鎳對自旋能隙溫度的抑制並不為缺氧所影響，但鐠對自旋能隙溫度的抑制則會因為缺氧而被破壞。The spin gap temperatures(Ts) in the normal state ofPr-doped(R1-xPrx)Ba2Cu3O7 and oxygen deficient samplesincluding RBa2Cu3O6+x(R = Yb, Er, Y, Ho, Dy, Gd, Eu, Sm,Nd), (Y0.8Gd0.2)Ba2Cu3O6+x, YBa2(Cu0.98Ni0.02)3O6+x and(R0.85Pr0.15)Ba2Cu3O6+x(R = Y,Gd), have been investigated. We intend to examine the mechanismof theso-called "spin gap" through the qualtative analysis ontherelationships between superconducting transitiontemperatures Tcand Ts of the samples mentioned above. In terms of therelationships between Tc and Ts ofoxygen deficient RBCOs withdifferent R-site rare earthelements, we find that elements onthe R sites don'taffect the spin gap temperatures in oxygendeficient pureRBCOs. However, Ts increase with increasing theionic size of R-site elements in Pr-doped RBCOs at a fixedPrconcentration. Besides, comparing the Ts of oxygendeficient pureRBCOs to those of Pr-doped RBCOs which are fullyoxygenated at the same Tc, we find that Pr atoms doped onthe Rsites will reduced the carrier density and cause thespin gap toopen, but simultaneously suppress Ts. Furthermore, Checkingthe Tc vs. Ts curves of oxygendeficient Ni- and Pr-doped YBCOs,we obtain that thesuppression which comes from Ni doping isn'taffected bythe oxygen deficiency, but the suppression due toPrdoping would be destroyed by the oxygen deficiency.