Abstract
In this work, we demonstrate a simple technique to grow high-quality whiskers of Bi2 Sr2 CaCu2 O8+δ – a high Tc superconductor. Structural analysis shows the single-crystalline nature of the grown whiskers. To probe electrical properties, we exfoliate these whiskers into thin flakes (~50 nm thick) using the scotch-tape technique and develop a process to realize good electrical contacts. We observe a superconducting critical temperature, Tc, of 86 K. We map the evolution of the critical current as a function of temperature. With 2-D materials emerging as an exciting platform to study low-dimensional physics, our work paves the way for future studies on two-dimensional high-Tc superconductivity.
Highlights
The isolation of graphene and other layered materials like transition metal dichalcogenides has ushered in a new era in the field of two-dimensional physics[1,2,3]
As BSCCO is a layered material, we exfoliate its whiskers into thin flakes and perform electrical transport measurements
In previous experiments on exfoliated BSCCO flakes, some groups observed superconductivity[15, 16], while some did not[3]. This is because of ambient exfoliation and processing that causes the degradation of the top layers of BSCCO thin flakes. To overcome this problem we have developed a fabrication scheme, where the BSCCO flakes are exfoliated inside a glove box in nitrogen environment and the top few layers are removed by in-situ Ar etching prior to the metal deposition for electrodes
Summary
The sample was held at 1100 °C for about 24 hours in order to achieve proper homogenization and splat quenched between two heavy copper plates, followed by cooling with liquid nitrogen This BSCCO shard was annealed at 875 °C for 10 days in a 50 sccm oxygen flow (purity of oxygen ~99.5%); the temperature variation in this critical growth cycle is shown in Fig. 1(b) in Supplementary material. Apart from the resistive jump at Ic, we see multiple steps in IVCs shown in Figs 3(b) and 4(a), which resemble phase-slip features[45,46,47,48] At these phase-slip features, the order parameter fluctuates locally and goes to zero, while the phase of the order parameter slips by 2 π, resulting in a finite voltage state. In this model the behavior of phase slip centers (PSCs) has been discussed, which appear in a localized region of coherence length, ξ, the measured voltage drop (a) 5 0 -5
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