Theory of tunneling conductance and surface-state transition in superconducting topological insulators

Yamakage, Ai; Yada, Keiji; Sato, Masatoshi; Tanaka, Yukio

doi:10.1103/physrevb.85.180509

Cited by 123 publications

(200 citation statements)

References 62 publications

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“…In this regard, the superconductor Cu x Bi 2 Se 3 , 270) which is a doped 3D TI, has attracted a lot of attention. 255,269,[271][272][273][274][275][276][277][278][279][280][281] In fact, Cu x Bi 2 Se 3 was recently found to present signatures of unconventional superconductivity in its point-contact spectra, 255) and an unconventional superconductivity in this material is necessarily topological for symmetry reasons. 255) It should be mentioned that the experimental situation for Cu x Bi 2 Se 3 is currently rather controversial.…”

Section: Majorana Fermionsmentioning

confidence: 99%

Topological Insulator Materials

2013

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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.

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Section: Majorana Fermionsmentioning

confidence: 99%

Topological Insulator Materials

2013

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“…Specifically, Andreev reflection features with the width corresponding to the induced gap in the normal material, along with a reduced gap in the superconductor, were shown to manifest the signature of the proximity effect 23,24,27,28 . Low-T c superconductivity has been observed recently in Cu x Bi 2 Se 3 29-31 , and a corresponding theory of unconventional superconductivity has been developed 32,33 . These low-T c studies provide the evidence for existence of interactions in TIs, enabling the possibility of inducing a superconducting gap in TIs in proximity with high-T c materials as well.…”

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confidence: 99%

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

et al. 2012

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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.

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“…(5) be homogeneous and the wave function ψ S be made to vanish [11] at the N/S boundary. This would be incorrect, however, as it would imply the conductance g s to vanish.…”

Section: The Andreev Problemmentioning

confidence: 99%

Effect of Majorana Fermions on Andreev Spectroscopy of Multiband Topological Superconductors

2015

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We introduce a model for a multiband topological superconductor with two orbitals per lattice site, in two spatial dimensions. Concentrating on the Andreev re ection problem, the appropriate wave function matching conditions for an interface with a normal single-band metal were previously derived in the framework of a quantum waveguide theory. This theory retrieves the correct number of Majorana fermion states as predicted by the topological index. We obtain the di erential conductance as a function of bias voltage, which displays the contribution of the Majorana fermions. Interface disorder is also considered. By varying band structure parameters, topological transitions can be induced, whereby the number of the Majorana modes varies. We calculate the e ect of such transitions on the di erential conductance.

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Theory of tunneling conductance and surface-state transition in superconducting topological insulators

Cited by 123 publications

References 62 publications

Topological Insulator Materials

Topological Insulator Materials

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

Effect of Majorana Fermions on Andreev Spectroscopy of Multiband Topological Superconductors

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