High-temperature superconductivity: the roles of oxide layers

Origin of the superconductivity in the Y-Sr-Ru-O and Y-Sr-Cu-O systems

“…Among them, there has been particular interest in the Ru-based double-perovskite structure Sr 2 YRuO 6 systems with minor Cu doping on Ru ion sites. [2][3][4][5] The parent insulator compounds Sr 2 YRuO 6 can be obtained from the itinerant ferromagnet SrRuO 3 by replacing each second Ru ion with a nonmagnetic Y ion. [6][7][8][9] The antiferromagnetic ͑AFM͒ transition temperature ͑T N ͒ is 26 K and there is a spin-flop-like transition below T M Ϸ 17 K. 8 An effective paramagnetic moment ef f was found to be 3.13 B /Ru 5+ , which was attributed a spin-orbit coupling.…”

“…Intriguingly, SC has been reported in Sr 2 YRu 1−x Cu x O 6−␦ ceramic materials with an onset transition temperature of T C Ϸ 45-49 K for x = 0.03-0.50. [2][3][4][5] Addressing the question of the nature of SC, Dow and Harshman 5,10,11 proposed a model in which superconducting condensation occurs in the SrO planes with the ͑Ru 1−x Cu x ͒O planes magnetically ordered.…”

“…Later, it was found that other ruthenates have very interesting magnetic and electric properties. Among them there has been particular interest in the Ru-based double perovskite structure Sr 2 YRuO 6 systems with minor Cu-doping on Ru ion sites [2][3][4][5].…”

Spin-glass behavior, spin fluctuations, and superconductivity inSr2Y(Ru1−uHarshman1, Kossler2, Greer3 et al. 2003Phys. Rev. B272180View full textAdd to dashboardCite

“…1 ͑Ref. 1͔͒ because it ͑i͒ has no cuprate planes, 2 ͑ii͒ superconducts at an onset temperature of T c Ϸ45-49 K, [3][4][5][6][7][8][9] ͑iii͒ has only two types of layers, (SrO) 2 and Y(Ru 1Ϫu Cu u )O 4 , ͑iv͒ superconducts in its SrO layers, 5 ͑v͒ exhibits ferromagnetism in the a-b planes of its Y(Ru 1Ϫu Cu u )O 4 layers, whose ferromagnetic moments alternate direction from one adjacent magnetic Y(Ru 1Ϫu Cu u )O 4 layer to the next, forming a net antiferromagnetic structure, 10 ͑vi͒ has Cu ions that spin order at Ϸ86 K, 9 and ͑vii͒ exhibits spin-glass behavior of its Y(Ru 1Ϫu Cu u )O 4 layers in a narrow range around 29.25 K ͑as we shall show here͒.…”

Electronic State Distributions of YBa2Cu3O7-x Laser-Ablated Plumes

“…[53] The commonly held view in the literature is that copper oxide planes are responsible for the supercurrent [18,20], however, an alternate explanation has been offered, which credits charge reservoir layers for carrying supercurrent. [16,24] Finally, oxygen stoichiometry has been shown to be important in the superconducting behavior of YBa 2 Cu 3 O 7−δ , with an optimum value of δ=0.12. [30] Practical application of YBCO as a superconducting wire poses significant manufacturing problems.…”