Conundrum of strongly coupled supercurrent flow in both under- and overdoped Bi-2212 round wires
نویسندگان
چکیده
Understanding what makes Bi$_2$Sr$_2$Ca$_1$Cu$_2$O$_x$ (Bi-2212) the only high critical current density ($J_c$), temperature superconductor (HTS) capable of being made as a round wire (RW) is important intellectually because $J_c$ RW Bi-2212 breaks paradigm that forces biaxially textured REBCO and uniaxially (Bi,Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$_x$ (Bi-2223) into tape geometries reproduce strong anisotropy native crystal structure force expensive fabrication routes to ensure best possible texture with minimum angle grain boundaries. The biaxial growth developed during partial melt heat treatment should favor $J_c$, even though its $\sim$15$^{\circ}$ full width at half maximum (FWHM) grain-to-grain misorientation well beyond commonly accepted strong-coupling range. Its ability be strongly overdoped valuable too, since underdoped cuprate boundaries are widely believed weakly linked. Accordingly, we here study property changes after oxygen underdoping optimized, wire. While vortex pinning diminish significantly in wires, were not able develop prominent weak-link signature (a hysteretic $J_c$(H) characteristic) evident very Bi-2223 tapes $\sim$ 15$^{\circ}$ FWHM uniaxial texture. We attribute lack weak link our wires high-aspect ratio, large-grain, basal-plane-faced morphology produced by partial-melt processing which enables $c$-axis Brick-Wall flow when $ab$-plane transport blocked. conclude presently optimized intrinsically constitutes coupled path, regardless doping state.
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ژورنال
عنوان ژورنال: Physical Review Materials
سال: 2021
ISSN: ['2476-0455', '2475-9953']
DOI: https://doi.org/10.1103/physrevmaterials.5.074803