Electron tunneling study of the superconducting proximity effect in Pb-Cd

Proximity-effect-induced superconductivity in topological insulator-related material Bi2Se3

“…Recently, a superconducting energy gap was observed in ultra-thin Bi 2 Se 3 films grown on a superconducting NbSe 2 substrate 9 . It proves that a PE-induced superconducting state can be formed in Bi 2 Se 3 films when the electrons there are confined to be close to the S-TI interface, similar to those reported in the early literature [5][6][7][8] . But it would still be interesting to investigate whether a superconducting state can be established in the TI side without the structural confinement to the electrons.…”

“…According to McMillan 4 , this energy gap could be established either through electron-electron (e-e) attractive interaction, or by confining the electrons into a narrow space close to the S-N interface (i.e., in a confined S-N structure), where S and N denote superconductor and normal metal, respectively. From the experimental side, the existence of a PE-induced gap [5][6][7][8][9] and the ability of carrying a supercurrent 8 have long been verified in confined S-N structures. However, in open S-N structures where the electrons in the normal metal are not necessarily confined near the interface, neither the existence of a PE-induced supercurrent-carrying state nor the existence of an energy gap has been verified experimentally by using independent probes/contacts, only a gap-like structure (i.e., not a true superconducting gap) was observed via a tunneling measurement 10 .…”

Superconducting Proximity Effect for In Situ and Model Layered Systems

“…For these junctions the N(w) data fit the MCMillan tunneling model [9] rather well and give values of~ ranging from 0.40 to 0.77 meV for a series of four films with different thickness combinations [8]. This is a direct experimental verification that the de Gennes boundary conditions are correct to about 20%.…”

Proximity-effect-induced superconducting phase in the topological insulator Bi2Se3

“…9 This proves that a PE-induced superconducting state can be formed in Bi 2 Se 3 films when the electrons there are confined to be close to the S-TI interface, similar to those reported in the early literature. [5][6][7][8] But it would still be interesting to investigate whether a superconducting state can be established in the TI side without the structural confinement to the electrons. And if yes, how far this state could survive away from the S-TI interface.…”

“…2,3 According to the theories, 4 this energy gap could be established either through electronelectron (e-e) attractive interaction, or by confining the electrons into a narrow space close to the S-N interface (i.e., in a confined S-N structure), where S and N denote superconductor and normal metal, respectively. From the experimental side, the existence of a PE-induced gap [5][6][7][8][9] and the ability of carrying a supercurrent 8 have long been verified in confined S-N structures. However, in open S-N structures where the electrons in the normal metal are not necessarily confined near the interface, neither the existence of a PE-induced supercurrent-carrying state nor the existence of an energy gap has been verified experimentally by using independent probes/contacts; only a gaplike structure (i.e., not a true superconducting gap) was observed via a tunneling measurement.…”