Interface superconductivity – Possible origin of high critical temperature in layered superconductors

Abstract

Superconducting transition temperatures T c of the YBCO film surface and of the YBCO film/substrate interface were measured inductively. It was observed that the interface-T c is always higher then the surface -T c . However deposition of silver over-layer enhances the superconducting transition temperatures. This observation was confirmed by four-point resistance measurements. In the annealed YBCO/Ag bilayers magnetic properties of the interface were observed. We believe that such phenomena are a common feature of layered systems. This two dimensional structure reminds the layered microstructure of the high-temperature superconductors and one can suppose that covering of the superconducting layer by non-superconducting layer is a condition for obtaining high critical temperatures in general.

Hidden order as a source of interface superconductivity

“…15 A slight increase of T c has been measured also in another high-T c superconductor-YBa 2 Cu 3 O 7 films covered by a thin Ag film. 16 A few decades ago, a similar effect has been observed in bilayers composed of conventional low-T c superconductors and normal metals. [17][18][19] These latter experiments were motivated by original Ginzburg's ideas on the possibility to get a surface superconductivity with a high transition temperature.…”

“…Note that ∆ 0 (x) has the shape of a soliton, whereas other solutions have nodes. (c) In the case of a weak suppression of W , one has a shallow 'potential' in the 'Schrödinger' equation and there exists only one 'energy' level given by Eq (16)…”

Magnetic properties of electrospun non-woven superconducting fabrics

“…An interesting feature is the observation that the magnetically determined critical temperature is lower than the one measured in resistance measurements on the same samples, 13 which is opposite of bulk samples, 14 but seen in thin film samples. 15,16 Possible reasons for this behavior may be surface superconductivity or an influence of the temperature dependence of the superconducting parameters λ and ξ, which bot raise towards the critical temperature, T c . This will be further investigated in the future.…”