Giant Proximity Effect in Cuprate Superconductors

Abstract

Using an advanced molecular beam epitaxy system, we have reproducibly synthesized atomically smooth films of high-temperature superconductors and uniform trilayer junctions with virtually perfect interfaces. We found that supercurrent runs through very thick barriers. We can rule out pinholes and microshorts; this "giant proximity effect" (GPE) is intrinsic. It defies the conventional explanation; it might originate in resonant tunneling through pair states in an almost-superconducting barrier. GPE may also be significant for superconducting electronics, since thick barriers are easier to fabricate.

Bose–Einstein condensation of strongly correlated electrons and phonons in cuprate superconductors

“…Hence the order parameter could penetrate into the normal cuprate semiconductor up to more than a thousand coherence lengths as observed [94]. If the thickness of the barrier L is small compared with Z * , and (μ) 1/2 ≪ 1, the order parameter decays following the power law, rather than exponentially,…”

“…Using an advanced molecular beam epitaxy, Bozovic et al [94] proved that this giant proximity effect (GPE) is intrinsic, rather than extrinsic caused by any inhomogeneity of the barrier. Hence GPE defies the conventional explanation, which predicts that the critical current should exponentially decay with the characteristic length of about the coherence length, which is ξ 1 nm in the cuprates.…”

Proximity-induced high-temperature superconductivity in the topological insulators Bi2Se3 and Bi2Te3

“…Nonetheless, all such experiments performed to date have employed low critical-temperature (low-T c ) materials that require extreme cooling, and the important ratio of the superconducting gap to the Fermi energy in such systems is very small. Inducing superconductivity with the larger energy scales and higher temperatures possible in high critical-temperature (high-T c ) superconductors 20 can enable future realizations of more practical devices, as well as greatly expand the ability to study the underlying physical phenomena 21 .…”

Low-temperature proximity effect in clean metals with repulsive electron-electron interaction

“…In particular, superconductor-ferromagnet structures, 2-6 cuprate junctions, [7][8][9] and mesoscopic SN structures [10][11][12][13] have been experimentally studied and addressed theoretically.…”