Superconducting proximity effect and possible evidence for Pearl vortices in a candidate topological insulator

Exotic excitations arise at the interface between a three-dimensional topological insulator (TI) and superconductors. For example, Majorana fermions with a linear dispersion, E ∼ k, exist in a short π Josephson junction on the TI surface. We show that in these systems, the Andreev bound states spectrum becomes nearly flat at zero energy when the chemical potential is sufficiently away from the Dirac point. The flat dispersion is well approximated by E ∼ k N , where N scales with the chemical potential. Similar evolution from linear to flat dispersion also occurs for the subgap spectrum of a periodic superconducting proximity structure, such as a TI surface in contact with a stripe superconductor.

show abstract

“…[19][20][21][22][23]. Gate tunable supercurrent has been observed and argued to be due to the TI surface state [19].…”

mentioning

confidence: 89%

Nearly flat Andreev bound states in superconductor-topological insulator hybrid structures

Lababidi

Zhao

2012

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…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.…”

Section: Majorana Fermionsmentioning

confidence: 99%

Topological Insulator Materials

2013

View full text Add to dashboard Cite

Topological insulators represent a new quantum state of matter which is characterized by peculiar edge or surface states that show up due to a topological character of the bulk wave functions. This review presents a pedagogical account on topological insulator materials with an emphasis on basic theory and materials properties. After presenting a historical perspective and basic theories of topological insulators, it discusses all the topological insulator materials discovered as of May 2013, with some illustrative descriptions of the developments in materials discoveries in which the author was involved. A summary is given for possible ways to confirm the topological nature in a candidate material. Various synthesis techniques as well as the defect chemistry that are important for realizing bulk-insulating samples are discussed. Characteristic properties of topological insulators are discussed with an emphasis on transport properties. In particular, the Dirac fermion physics and the resulting peculiar quantum oscillation patterns are discussed in detail. It is emphasized that proper analyses of quantum oscillations make it possible to unambiguously identify surface Dirac fermions through transport measurements. The prospects of topological insulator materials for elucidating novel quantum phenomena that await discovery conclude the review.

show abstract

“…This proximity effect has been proposed as a powerful resource for practical applications in optoelectronics 3 and has been predicted to produce the elusive Majorana fermion 4 by combining a superconductor with a topological insulator (TI) [5][6][7][8][9][10] . These goals have been pursued actively, including the recent demonstrations of novel semiconductor light sources 11 and induced superconductivity in TIs [12][13][14][15][16] such as Bi 2 Se 3 and Bi 2 Te 3 , which have been shown to have topologically protected surface states [17][18][19] . 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.…”

mentioning

confidence: 99%

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

et al. 2012

View full text Add to dashboard Cite

Interest in the superconducting proximity effect has been reinvigorated recently by novel optoelectronic applications as well as by the possible emergence of the elusive majorana fermion at the interface between topological insulators and superconductors. Here we produce high-temperature superconductivity in Bi 2 se 3 and Bi 2 Te 3 via proximity to Bi 2 sr 2 CaCu 2 o 8 + δ , to access higher temperature and energy scales for this phenomenon. This was achieved by a new mechanical bonding technique that we developed, enabling the fabrication of highquality junctions between materials, unobtainable by conventional approaches. We observe proximity-induced superconductivity in Bi 2 se 3 and Bi 2 Te 3 persisting up to at least 80 K-a temperature an order of magnitude higher than any previous observations. moreover, the induced superconducting gap in our devices reaches values of 10 mV, significantly enhancing the relevant energy scales. our results open new directions for fundamental studies in condensed matter physics and enable a wide range of applications in spintronics and quantum computing.

show abstract

Superconducting proximity effect and possible evidence for Pearl vortices in a candidate topological insulator

Cited by 138 publications

References 35 publications

Nearly flat Andreev bound states in superconductor-topological insulator hybrid structures

Nearly flat Andreev bound states in superconductor-topological insulator hybrid structures

Topological Insulator Materials

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

Contact Info

Product

Resources

About