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

Abstract

We have studied the electron transport properties of topological insulator-related material Bi 2 Se 3 near the superconducting Pb-Bi 2 Se 3 interface, and found that a superconducting state is induced over an extended volume in Bi 2 Se 3 . This state can carry a Josephson supercurrent, and demonstrates a gaplike structure in the conductance spectra as probed by a normal-metal electrode. The establishment of the gap is not by confining the electrons into a narrow space close to the superconductor-normal metal interface, as previously observed in other systems, but presumably via electron-electron attractive interaction in Bi 2 Se 3 .

Topological Insulator Materials

“…6) It is useful to note that such a proximity-induced superconducting state on the surface of a TI has singlet Cooper pairs, but nonetheless it is topologically nontrivial due to the Berry phase born by the surface Dirac electrons; therefore, such a surface can be considered a 2D topological superconductor. There have been a number of experimental reports to confirm the superconducting proximity effect in the topological surface states, 171,231,[260][261][262][263][264][265][266][267][268] but the existence of Majorana fermions has not been elucidated.…”

Superconductivity in textured Bi clusters/Bi2Te3 films

“…21 In regard to this mechanism, the induced superconducting regions [(adjacent to the Bi clusters/Bi 2 Te-3 interfaces, orange regions in Fig. 4(g)] can be established inside the Bi 2 Te 3 films.…”

Fermi-level electronic structure of a topological-insulator/cuprate-superconductor based heterostructure in the superconducting proximity effect regime

“…Thus although progress has been reported by using conventional transport and STM experiments [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] , those studies do not have the momentum resolution necessary to distinguish the contribution to the STM or transport signals of the topological surface states from that of the bulk or impurity bands. In fact, it has been recently shown [27][28][29][30] that the undesirable superconductivity in the bulk and impurity bands can lead to ambiguous interpretation of the transport and STM data regarding Majorana fermions.…”