Fabrication of Bi2212 Cross Whiskers Junction

An intrinsic Josephson junction has been successfully fabricated without any micro-fabrication technique. Two Bi2212 whiskers were crossed with one another and joined by post-annealing. The inter-whisker electrical transport properties were measured by the four-probe method. The temperature dependence of resistance exhibited metallic behavior above TC. The resistance decreased to zero around 80K, corresponding to the superconducting transition. The current-voltage characteristics at 5K exhibited a small hysteresis and voltage jump, which can be explained by the intrinsic Josephson effect.Comment: 3 page PDF fil

A Cross-Whiskers Junction as a Novel Fabrication Process for Intrinsic Josephson Junction

A Bi2Sr2CaCu2O8+d cross-whiskers junction has been successfully discovered as a novel intrinsic Josephson junction without using any technique for micro-fabrication. Two Bi2Sr2CaCu2O8+d whisker crystals were placed crosswise on a MgO substrate and heated at 850C for 30 min. They were electrically connected at their c-planes. The measurement terminals were made at the four ends of the whiskers. The I-V characteristics of the cross-whiskers junction at 5K were found to show a clear multiple-branch structure with a spacing of approximately 15 mV that is a feature of the intrinsic Josephson junction. The critical current density Jc was estimated to be 1170 A/cm2. The branch-structure was strongly suppressed by the magnetic field above 1kOe.Comment: 4 pages, PDF fil

Synthesis of YNi2B2C thin films by magnetron sputtering

Thin films of YNi2B2C superconductor by the magnetron sputtering technique have been synthesized. The YNi2B2C phase was found to crystallize very uniformly after annealing at 1050 °C in vacuum. The structure was investigated and the electric and magnetic properties were characterized. The films were c-axis oriented and showed a Tc onset of ~15 K by both magnetization and resistivity measurements. The results of the critical current measurement suggested the existence of anisotropies of pinning force and an upper critical field Bc2

d-like Symmetry of the Order Parameter and Intrinsic Josephson Effects in Bi2212 Cross-Whisker Junctions

An intrinsic tunnel junction was made using two Bi-2212 single crystal whiskers. The two whiskers with a cross-angle were overlaid at their c-planes and connected by annealing. The angular dependence of the critical current density along the c-axis is of the d-wave symmetry. However, the angular dependence is much stronger than that of the conventional d-wave. Furthermore, the current vs. voltage characteristics of the cross-whiskers junctions show a multiple-branch structure at any cross-angle, indicating the formation of the intrinsic Josephson junction array.Comment: 4 pages PDF fil

Epitaxial Non <i>c</i>-Axis <i>Twin-Free</i> Bi₂Sr₂CaCu₂O_8+δ Thin Films for Future THz Devices

Thin films of (117) Bi2Sr2Ca2CuO8+&#948; (Bi-2212) were grown by Molecular Organic Chemical Vapor Deposition (MOCVD) on (110) SrTiO3 and (110) LaAlO3 substrates. Substrates were vicinal with off angles up to 20&#176;. Films are 3D epitaxial and X-ray diffraction &#966;-&#968; scans demonstrate that, while the films grown on a flat substrate are composed of twinned grains, the films on vicinal substrate are twin-free. A higher quality is obtained if growth is performed at two temperatures: Growth starts at 550&#8211;600 &#176;C and continues at 700&#8211;750 &#176;C. The twin-free film grown by the two-temperature method shows a zero-resistance critical temperature of 37 and 32 K when the measuring current is applied in-plane parallel and perpendicular to [001] direction of the substrate. Twin-free non c-axis thin films are promising for fabrication of novel planar THz devices

Novel fabrication method of self-organized FePd multilayer nanodots using the agglomeration of Au/Fe bilayer films

Ha J-G, Koo J, Koo S-M, Arisawa S, Koh J-H, Kamiko M. Novel fabrication method of self-organized FePd multilayer nanodots using the agglomeration of Au/Fe bilayer films. JAPANESE JOURNAL OF APPLIED PHYSICS. 2017;56(7): 070312.We fabricated self-organized FePd multilayer films with specific nanostructures by using Au/Fe bilayer films as a template. Au/Fe bilayer films were prepared as a template layer by forming a self-organized nanostructure through the agglomeration phenomenon. Using this Au/Fe bilayer as a template, FePd multilayers were deposited. The surface morphologies of FePd multilayer closely resembled the self-organized Au/Fe bilayer. As a result, we successfully manufactured self-organized FePd nanodots, with a shape closely resembling that of the agglomerated Au/Fe bilayer. In addition, it is confirmed that the agglomerated FePd nanodots were formed in the L1(0) phase by annealing at 350 degrees C. (C) 2017 The Japan Society of Applied Physics

Growth of single-crystal Ca10(Pt4As8)(Fe1.8Pt0.2As2)5 nanowhiskers with superconductivity up to 33 K

Single-crystal Ca(10)(Pt(4)As(8))(Fe(1.8)Pt(0.2)As(2))(5) superconducting (SC) nanowhiskers with widths down to hundreds of nanometers were successfully grown in a Ta capsule in an evacuated quartz tube by a flux method. Magnetic and electrical properties measurements demonstrate that the whiskers have excellent crystallinity with critical temperature of up to 33 K, upper critical field of 52.8 T, and critical current density of J(c) of 6.0 x 10(5) A/cm(2) (at 26 K). Since cuprate high-T(c) SC whiskers are fragile ceramics, the present intermetallic SC whiskers with high T(c) have better opportunities for device applications. Moreover, although the growth mechanism is not understood well, the technique can be potentially useful for growth of other whiskers containing toxic elements