Papers by Keyword: HTSC

Abstract: The suppression of superconductivity (T_c) in electron-doped superconducting materials Eu_1.81Ce_0.19Cu_1-yZn_yO_4+α-δ (ECCZO) heavily overdoped regimes by nonmagnetic impurity Zn with concentration of y = 0, 0.01, 0.02, and 0.03 has been successfully investigated by using XRD and SQUID measurements. All samples were synthesized using the solid-state reaction method. The crystal structure obtained from XRD measurements has a tetragonal T° structure, which matches the crystal structure of electron-doped superconductors in general. The addition of Zn impurity shows no change in the crystal structure, but there is a decrease in the α-lattice and an increase in the c-lattice, unit cell volume, and Cu-O bond length. This causes the distance between the charge reservoir and the conduction layer to increase and affects the disappearance of T_c. Magnetic susceptibility measurements using SQUID were carried out under FC (Field Cooling) conditions with temperatures between 2 - 30 K with a field of 5 Oe. The sample with y = 0 has diamagnetic properties with a superconductivity value (T_c) of about 11 K. The addition of Zn impurities succeeded in suppressing superconductivity as indicated by the disappearance of T_c, so that the sample is in the ground state. The Curie constant and the effective magnetic moment decrease with increasing Zn concentration. This is probably due to the decrease in Cu²⁺ when the non-magnetic Zn²⁺ atoms were added, therefore the overall value of the µ_eff decreases when Zn²⁺ substitutes some Cu²⁺. This result is different from that described by Abrikosov-Gor’kov theory in the hole-doped high-T_c cuprates.

Abstract: In view of the difficulty of designing a high-order linear phase filter with prototype parameters directly, this paper proposes a new approach to rapidly construct a high order linear phase filter through cascading two same low-order linear phase filters. A twelve-order HTSC cascaded linear phase filter is fabricated on YBCO/LaAlO3/YBCO substrate with the dimension of 44.1mm ×31.4mm. The measured result shows that the filter has a 56 MHz passband at a center frequency of 1993 MHz. The minimum insertion loss in the passband is 0.59 dB. The group delay variation in passband is less than 5 ns over 78.5% of the filter bandwidth which is in good agree with the simulation result.

Abstract: The samples of Gd1-xPrxBa2Cu3O7-δ with compositions x = 0.0, 0.1 & 0.3 were prepared by ceramic route. The XRD study of all samples is carried out. The XRD studies of the samples prepared by ceramic route show GdPr-123 system have an orthorhombic pervoskite structure. The lattice parameters, oxygen content, volume of unit cell, orthorhombic distortion, hole concentration in CuO2 plane and charge on Cu-O plane were evaluated using XRD data. It is found that the lattice parameters, volume of unit cell increase while oxygen content orthorhombic distortion, hole concentration (Psh) and average charge (p) decrease as doping percentage of Pr increases. The resistivity measurement shows the transition temperature decreases while transition width increases with increasing Pr concentration. The suppression of superconductivity may be due to reduction in hole concentration or magnetic pair breaking. We report such qualitative results of Pr substituted Gd-123 in this paper quantitatively.