Artificial Topological Superconductor by the Proximity Effect

Abstract

Topological superconductors (TSCs), featuring fully gapped bulk and gapless surface states as well as Majorana fermions, have potential applications in fault-tolerant topological quantum computing. Because TSCs are very rare in nature, an alternative way to study the TSC is to artificially introduce superconductivity into the surface states of a topological insulator through the proximity effect ]. Here we report the experimental realization of the proximity effect-induced TSC in Bi 2 Te 3 thin films grown on a NbSe 2 substrate, as demonstrated by the density of states probed using scanning tunneling spectroscopy. We observed Abrikosov vortices and Andreev lower energy bound states on the surface of the topological insulator, with the superconducting coherence length depending on the film thickness and the magnetic field. These results also indicate that the topological surface states of Bi 2 Te 3 thin films are superconducting and, thus, that the Bi 2 Te 3 =NbSe 2 is an artificial TSC. The feasibility of fabricating a TSC with an individual Majorana fermion bound to a superconducting vortex for topological quantum computing is discussed.

Indium Substitution Effect on the Topological Crystalline Insulator Family (Pb1−xSnx)1−yInyTe: Topological and Superconducting Properties

“…A plausible strategy of looking for Majorana fermions is to artificially construct topological insulator/conventional superconductor heterostructures and make use of the superconducting proximity effect [72][73][74][75][76][77]. Both SIT and PSIT would be perfect platforms for this purpose, since these systems undergo a continuous change from a TCI to a (likely conventional) superconductor.…”

Detection of Majorana zero mode in the vortex

“…15,16 The successful fabrication of such heterostructure built a promising platform for the detection of MZMs. Here we review the material properties and growth procedures of the heterostructure and discuss some details of the heterostructure that are significant in the detection of the MZMs.…”

“…Growing TI on SC was proved to be much easier. 14,15 In this artificial TSC, two well-separated MZMs exist in a vortex core on both top and bottom surface of TI thin films. 35 As shown in Fig.…”

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.…”