Serena Eley

Approaching zero-temperature metallic states in mesoscopic superconductor-normal-superconductor arrays

It has long been debated whether it is possible to approach a zero-temperature metallic state in a two-dimensional system. A study of the electrical characteristics of arrays of superconducting islands of varying thickness and spacing on a normal metal film suggests it is.

Rapid doubling of the critical current of YBa2Cu3O7-δ coated conductors for viable high-speed industrial processing

We demonstrate that 3.5-MeV oxygen irradiation can markedly enhance the in-field critical current of commercial second generation superconducting tapes with an exposure time of just 1 s per 0.8 cm2. The speed demonstrated here is now at the level required for an industrial reel-to-reel post-processing. The irradiation is made on production line samples through the protective silver coating and does not require any modification of the growth process. From TEM imaging, we identify small clusters as the main source of increased vortex pinning.

Engineered Pinning Landscapes for Enhanced 2G Coil Wire

We demonstrate a twofold increase in the in-field critical current of AMSCs standard 2G coil wire by irradiation with 18-MeV Au ions. The optimum pinning enhancement is achieved with a dose of 6 × 1011 Au ions/cm2. Although the 77 K, self-field critical current is reduced by about 35%, the in-field critical current (H//c) shows a significant enhancement between 4 and 50 K in fields > 1 T. The process was used for the roll-to-roll irradiation of AMSCs standard 46-mm-wide production coated conductor strips, which were further processed into standard copper laminated coil wire. The long-length wires show the same enhancement as attained with short static irradiated samples. The roll-to-roll irradiation process can be incorporated in the standard 2G wire manufacturing, with no modifications to the current process. The enhanced performance of the wire will benefit rotating machine and magnet applications.

Decoupling and tuning competing effects of different types of defects on flux creep in irradiated YBa2Cu3O7-δ coated conductors

YBa2Cu3O7−δ coated conductors (CCs) have achieved high critical current densities (J c) that can be further increased through the introduction of additional defects using particle irradiation. However, these gains are accompanied by increases in the flux creep rate, a manifestation of competition between the different types of defects. Here, we study this competition to better understand how to design pinning landscapes that simultaneously increase J c and reduce creep. CCs grown by metal organic deposition show non-monotonic changes in the temperature-dependent creep rate, S(T). Notably, in low fields, there is a conspicuous dip to low S as the temperature (T) increases from ~20 to ~65 K. Oxygen-, proton-, and Au-irradiation substantially increase S in this temperature range. Focusing on an oxygen-irradiated CC, we investigate the contribution of different types of irradiation-induced defects to the flux creep rate. Specifically, we study S(T) as we tune the relative density of point defects to larger defects by annealing both an as-grown and an irradiated CC in O2 at temperatures T A = 250 °C–600 °C. We observe a steady decrease in S(T > 20 K) with increasing T A, unveiling the role of pre-existing nanoparticle precipitates in creating the dip in S(T) and point defects and clusters in increasing S at intermediate temperatures.

Nuclear magnetic resonance investigation of the heavy fermion system Ce 2 CoAl 7 Ge 4

We present nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) measurements performed on single crystalline \ccag{}, a member of a recently discovered family of heavy fermion materials Ce

Physical properties of the Ce2MAl7Ge4 heavy-fermion compounds (M=Co,Ir,Ni,Pd)

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Dependence of global superconductivity on inter-island coupling in arrays of long SNS junctions

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Accelerated vortex dynamics across the magnetic 3D-to-2D crossover in disordered superconductors

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Glassy Dynamics in a heavy ion irradiated NbSe 2 crystal

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Author Correction: Glassy Dynamics in a heavy ion irradiated NbSe 2 crystal

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