Large critical magnetic field and tunneling anomaly behavior of superconducting carbon-coated Sn nanorods and nanoparticles

Abstract

Ac susceptibility studies of a superconducting gallium nanocomposite: Crossover in the upper critical field line and activation barriers Evidence that the upper critical field of Nb3Sn is independent of whether it is cubic or tetragonal Appl. Phys. Lett. 99, 122507 (2011); 10.1063/1.3643055Quasiperiodic superconducting V/Zr multilayers: critical magnetic fields and crossover Low Temp.The arc-discharge process is usually used to synthesize some kinds of metal nanocrystals or nanoparticles all with high melting temperature. Here, the carbon-coated Sn ͑with a low melting temperature͒ nanostructured materials with different shapes, such as carbon-coated Sn nanorods with diameter of about 100 and 50 nm and, correspondingly, the length of 500 and 200 nm, and the carbon-coated Sn nanoparticles, are prepared by a modified arc-discharge process. The carbon shells are found to surround these Sn nanostructures. The carbon shell becomes thick with decreasing the size of the Sn nanostructures. The magnetic and electrical transports are affected by the shape of nanocrystals. The critical magnetic field of the carbon-coated Sn nanorods with diameter of 50 nm and length of 200 nm is almost 25 times higher than that of bulk Sn. The superconductivity of the carbon-coated Sn nanoparticles with particle size of 40 nm is destroyed. The zero bias tunneling anomalies was observed in the carbon-coated Sn nanoparticles.

Facile synthesis of superconducting NbN nanoparticles

“…The T C (15.1 K) of the as-prepared NbN nanoparticles is slightly less than that of 17 K for a bulk NbN. The size distribution (5-15 nm) of the NbN nanoparticles obtained in this work is comparable with the corresponding temperature-dependent coherent length, leading to the experience suppression in the superconducting transition temperature [18,19]. The superconducting transition temperature T c of the nanoparticles as a function of their size d has been studied both theoretically and experimentally.…”

“…After the chamber was evacuated to 5.8 Â 10 À 3 Pa, a mixture of H 2 (0.04 MPa), Ar (0.16 MPa) and N 2 (0.48 MPa) was introduced into the chamber. Then the arc was ignited and the current was maintained at 100 A for 2 h. After being passivated in 0.12 MPa N 2 for 24 h, products were collected from the water-cooling copper crucible in front of the target, which was different from the conventional water-cooling top and chamber wall [16][17][18][19].…”

“…The arc-discharge method was described elsewhere [16][17][18][19]. In the purified argon atmosphere, an anode Nb ingot was prepared by melting Nb flakes of 99.9 wt% purity by arc discharge.…”

Buildup of Sn@CNT nanorods by in-situ thermal plasma and the electronic transport behaviors

“…Such a similar behavior was also observed in a graphene-metal hybrid [36] or a Josephson junction array [37]. For the present Sn@CNT NRs, Josephson junction of Sn/CNT/Sn layered structure and the weakly linked nanocapsules are essential in nanoscale [14].…”

“…It has been reported that the superconductivity of carbon-coated Sn@C NCs will be destroyed as the size decreases down to 40 nm. However, it has also been demonstrated for the carbon-coated Sn nanorods with diameter of 50 nm and length of 200 nm, the critical magnetic field is almost 25 times higher than that of bulk Sn [14]. Large electrical current was also detected for MWCNTs encapsulated Sn nanowire, which can raise a local heating and in turn suppresses the superconductivity [15].…”