Two-step growth of high-quality Nb/(Bi0.5Sb0.5)2Te3/Nb heterostructures for topological Josephson junctions

Zhang, Hui; Ma, Xiaodong; Li, Lin; Langenberg, Deler; Zeng, Chang Gan; Miao, Guo Xing

doi:10.1557/jmr.2018.195

Cited by 7 publications

(4 citation statements)

References 37 publications

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“…Our proposal has clear advantages in experimental accessibility. The Josephson current on the surface of the 3DTI has been experimentally observed, where Josephson junction Nb/epitaxial (Bi 0.5 Sb 0.5 ) 2 Te 3 /Nb in the two steps have been fabricated and good I-V characteristics presented [11]. Also, tunneling conductance spectroscopy has been performed across hetero-Nb/topological insulator/Au, recently [38].…”

Section: Discussionmentioning

confidence: 99%

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Mass-like band-gap creation in superconducting topological insulator due to mixed singlet and triplet states

Khezerlou

Goudarzi

2019

J. Phys.: Condens. Matter

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We investigate proximity-induced mixed spin-singlet and spin-triplet superconducting state on the surface states of a topological insulator. Such hybrid structure features fundamentally distinct electron–hole excitations and resulting effective superconducting subgap. Studying the particle-hole and time-reversal symmetry properties of the mixed state Dirac–Bogoliubov–de Gennes effective Hamiltonian gives rise to manifesting possible topological phase exchange of surface states, since the mixed-spin channels leads to appearance of a band gap on the surface states. This can be verified by evaluating topological invariant winding number for chiral eigenstates, via the introducing a chiral symmetry operator. We interestingly find the role of mixed-spin superconducting state as creating a mass-like gap in topological insulator by means of appearing new mixed-spin channels and . The interplay between superconducting spin-singlet and triplet correlations actually results in gaped surface states, where the size of gap can be controlled by tuning the relative s- and p -waves pairing potentials. We show that the system is in different topology classes by means of using chiral or no-chiral spin-triplet symmetry. In addition, the resulting effective superconductor subgap manipulated at the Fermi surface presents a complicated dependency on mixed-spin channels. Furthermore, we investigate the resulting subgap tunneling conductance in N/S, and also Josephson current in S/I/S junctions to unveil the influence of effective symmetry of mixed superconducting gap. The results can pave the way to realize the effective superconducting gap in noncentrosymmetric superconductors with mixed-spin state.

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Section: Discussionmentioning

confidence: 99%

“…Moreover, superconductivity induction by proximity-effect on the surface states of a 3DTI has been of noticeable importance during the last decade. Several experimental probes [9][10][11][12][13][14][15] have evidenced existence of spin-singlet and spin-triplet pairing states in the…”

mentioning

confidence: 99%

Mass-like band-gap creation in superconducting topological insulator due to mixed singlet and triplet states

Khezerlou

Goudarzi

2019

J. Phys.: Condens. Matter

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“…The remarkable electrical tunability of CTJJ allows for the realization of Floquet chiral TSC physics, with the Josephson DC voltage being the key control knob. We note that the topological insulator-superconductor sandwich structures have already been fabricated experimentally with either Pb [36] or Nb [37] as the superconductor layers. Meanwhile, magnetic topological insulator-superconductor heterostructures have been realized in experiments with thin films of Cr-doped (Bi,Sb) 2 Te 3 and Nb [38][39][40].…”

mentioning

confidence: 96%

Anomalous Floquet Chiral Topological Superconductivity in a Topological Insulator Sandwich Structure

Zhang,

Sarma

2020

Preprint

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We show that Floquet chiral topological superconductivity arises naturally in Josephson junctions made of magnetic topological insulator-superconductor sandwich structures. The Josephson phase modulation associated with an applied bias voltage across the junction drives the system into the anomalous Floquet chiral topological superconductor hosting chiral Majorana edge modes in the quasienergy spectrum, with the bulk Floquet bands carrying zero Chern numbers. The bias voltage acts as a tuning parameter enabling novel dynamical topological quantum phase transitions driving the system into a myriad of exotic Majorana-carrying Floquet topological superconducting phases. Our theory establishes a new paradigm for realizing Floquet chiral topological superconductivity in solid-state systems, which should be experimentally directly accessible.

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“…We note that the topological insulator-superconductor sandwich structures have been successfully fabricated in the experiment. [102][103][104] To be specific, a topological superconducting phase with gapless helical Majorana edge modes is created when the phase difference of the junction is 𝜋 [see Figs. .…”

mentioning

confidence: 99%

Majorana Corner Modes and Flat-Band Majorana Edge Modes in Superconductor/Topological-Insulator/Superconductor Junctions

Xiaoting

Liu

et al. 2023

Chinese Phys. Lett.

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Recently, superconductors with higher-order topology have stimulated extensive attention and research interest. Higher-order topological superconductors exhibit unconventional bulk-boundary correspondence, thus allow exotic lower-dimensional boundary modes, such as Majorana corner and hinge modes. However, higher-order topological superconductivity has yet to be found in naturally occurring materials. In this work, we investigate higher-order topology in a two-dimensional Josephson junction comprised of two s-wave superconductors separated by a topological insulator thin film. We found that zero-energy Majorana corner modes, a boundary fingerprint of higher-order topological superconductivity, can be achieved by applying magnetic field. When an in-plane Zeeman field is applied to the system, two corner modes appear in the superconducting junction. Furthermore, we also discover a two dimensional nodal superconducting phase which supports flat-band Majorana edge modes connecting the bulk nodes. Importantly, we demonstrate that zero-energy Majorana corner modes are stable when increasing the thickness of topological insulator thin film.

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Two-step growth of high-quality Nb/(Bi_0.5Sb_0.5)₂Te₃/Nb heterostructures for topological Josephson junctions

Abstract: Abstract

Cited by 7 publications

References 37 publications

Mass-like band-gap creation in superconducting topological insulator due to mixed singlet and triplet states

Mass-like band-gap creation in superconducting topological insulator due to mixed singlet and triplet states

Anomalous Floquet Chiral Topological Superconductivity in a Topological Insulator Sandwich Structure

Majorana Corner Modes and Flat-Band Majorana Edge Modes in Superconductor/Topological-Insulator/Superconductor Junctions

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