Josephson Junctions (JJ) can be considered as two superconducting materials separated by a thin layer of insulator. By applying an electrical voltage at the heads of a series of JJ, an alternating current is generated, whose oscillation frequency is proportional to the applied voltage and is in the range of Terahertz (THz). Stacks of Intrinsic Josephson Junctions (IJJ) with atomic size are naturally present in layered high-Tc superconductors (HTSC) such as Y1Ba2Cu3O7-δ (Y-123) and Bi2Sr2CaCu2O8+δ (Bi-2212). Among the possible IJJ applications, high frequency devices can take advantage from the large Josephson plasma frequency found in some HTSC IJJs. In particular, Y-123 has the highest Josephson plasma frequency and its properties can be modulated, for instance, by cationic substitutions, as already noticed for Pb-doped Bi-2212. In view of a future exploitation of IJJ, HTSC whiskers, that are multilayered single crystals characterized by an highly crystalline nature, low defects concentration and excellent superconducting features, like the ones belonging to the Y-123 system, are ideal structures for the study and the design of THz devices based on IJJ. Within this context, we investigated the effect of chemical cationic substitutions as Al, Sb, Te, Ca and Pb, of anionic doping (O2) and of X-ray nanobeam irradiation on both the electrical and the structural properties of Y-123, Bi-2212 and Bi2Sr2Ca2Cu3O10+x (Bi-2223). In this work, we present some structural and superconducting modulations induced on Y-123 by chemical doping with Ca, Al, Te and Sb to improve chemical properties, physical properties and modulation of IJJ's stacks along the structure. The effects of the elemental incorporation in the structure have been investigated using single crystal X-ray diffraction technique and SEM/EDS measurements to obtain information on cationic distribution. In particular, single crystal X-ray diffraction successfully correlate the cationic insertion with the substitution sites, highlighting sometimes a modification of coordination frameworks of Cu. The electrical characterization R-T indicates corresponding changes in the conducting properties of the materials.
X-ray structures of single crystal high-Tc superconductors (HTSC) modulated by chemical substitutions
PASCALE, LISE;AGOSTINO, Angelo;TRUCCATO, Marco;OPERTI, Lorenza
2014-01-01
Abstract
Josephson Junctions (JJ) can be considered as two superconducting materials separated by a thin layer of insulator. By applying an electrical voltage at the heads of a series of JJ, an alternating current is generated, whose oscillation frequency is proportional to the applied voltage and is in the range of Terahertz (THz). Stacks of Intrinsic Josephson Junctions (IJJ) with atomic size are naturally present in layered high-Tc superconductors (HTSC) such as Y1Ba2Cu3O7-δ (Y-123) and Bi2Sr2CaCu2O8+δ (Bi-2212). Among the possible IJJ applications, high frequency devices can take advantage from the large Josephson plasma frequency found in some HTSC IJJs. In particular, Y-123 has the highest Josephson plasma frequency and its properties can be modulated, for instance, by cationic substitutions, as already noticed for Pb-doped Bi-2212. In view of a future exploitation of IJJ, HTSC whiskers, that are multilayered single crystals characterized by an highly crystalline nature, low defects concentration and excellent superconducting features, like the ones belonging to the Y-123 system, are ideal structures for the study and the design of THz devices based on IJJ. Within this context, we investigated the effect of chemical cationic substitutions as Al, Sb, Te, Ca and Pb, of anionic doping (O2) and of X-ray nanobeam irradiation on both the electrical and the structural properties of Y-123, Bi-2212 and Bi2Sr2Ca2Cu3O10+x (Bi-2223). In this work, we present some structural and superconducting modulations induced on Y-123 by chemical doping with Ca, Al, Te and Sb to improve chemical properties, physical properties and modulation of IJJ's stacks along the structure. The effects of the elemental incorporation in the structure have been investigated using single crystal X-ray diffraction technique and SEM/EDS measurements to obtain information on cationic distribution. In particular, single crystal X-ray diffraction successfully correlate the cationic insertion with the substitution sites, highlighting sometimes a modification of coordination frameworks of Cu. The electrical characterization R-T indicates corresponding changes in the conducting properties of the materials.
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
