Strong surface-pinning effects in polycrystalline HgBa2CuO4+δ superconductors
Yang Ren Sun, J. R. Thompson, H. R. Kerchner, D. K. Christen, M. Paranthaman, J. Brynestad
DOI 10.1103/PhysRevB.50.3330 · Physical Review B
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Abstract
Magnetic studies on polycrystalline HgCa2CuO4+δ superconductors reveal pronounced pinning by the grain surfaces at low temperatures over a wide range of magnetic fields. The response to small ac fields shows that up to 80% of the width of the dc magnetic hysteresis loop in high fields originates from shielding supercurrent flowing in the surface sheath, a vortex-free region with thickness of ∼10 nm. At 10 K and 15 kG, the observed persistent surface current has a density of ∼5×107 A/cm2 when averaged over the barrier thickness. The study suggests that a high current density may be achieved in very thin films by surface pinning.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| HgBa2CuO4+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 94 | Pressure unresolved | onset |
| HgBa2Ca2Cu3O8+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 134 | Pressure unresolved | unknown |
| HgBa2Ca2Cu3O8+δ Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 164 | Pressure not reported | unknown |
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