Superconductivity in textured Bi clusters/Bi2Te3 films

Le, Phuoc Huu; Tzeng, Wen Yen; Chen, Hsueh Ju; Luo, Chih-Wei; Lin, Jiunn‐Yuan; Leu, Jihperng

doi:10.1063/1.4894779

Cited by 13 publications

(4 citation statements)

References 40 publications

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“…When considering the average λ of Bi 2 Te 3 (111), our measurements suggest a rather modest e-ph coupling in agreement with other studies (Table I). While it is difficult to directly relate superconducting states with the e-ph coupling of a surface, the fact that Bi 2 Te 3 does not exhibit a superconducting phase under "normal" conditions 62,63 supports our results. Hence our finding of a modest λ is not surprising even though some individual phonons may provide a much larger e-ph interaction as reported by Howard et al 15 .…”

Section: E Electron-phonon Coupling From the Debye-waller Factorsupporting

confidence: 82%

Electron-phonon coupling and surface Debye temperature of Bi2Te3 (111) from helium atom scattering

et al. 2017

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We have studied the topological insulator Bi2Te3(111) by means of helium atom scattering. The average electron-phonon coupling λ of Bi2Te3(111) is determined by adapting a recently developed quantum-theoretical derivation of the helium scattering probabilities to the case of degenerate semiconductors. Based on the Debye-Waller attenuation of the elastic diffraction peaks of Bi2Te3 (111), measured at surface temperatures between 110 K and 355 K, we find λ to be in the range of 0.04 − 0.11. This method allows to extract a correctly averaged λ and to address the discrepancy between previous studies. The relatively modest value of λ is not surprising even though some individual phonons may provide a larger electron-phonon interaction. Furthermore, the surface Debye temperature of Bi2Te3(111) is determined as ΘD = (81 ± 6) K. The electronic surface corrugation was analysed based on close-coupling calculations. By using a corrugated Morse potential a peak-to-peak corrugation of 9% of the lattice constant is obtained.

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Section: E Electron-phonon Coupling From the Debye-waller Factorsupporting

confidence: 82%

Electron-phonon coupling and surface Debye temperature of Bi2Te3 (111) from helium atom scattering

et al. 2017

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“…Superconductivity was observed in otherwise nonsuperconducting TIs Bi 2 T e 3 and Bi 2 Se 3 . It was noticed very recently 28,29 that Bi nanoclusters naturally aggregate on the surface of Bi 2 T e 3 thin film and an explanation was put forward that the nanoclusters become superconducting and induce surface superconductivity in TI by the proximity effect. We speculate that the nanoclusters are not superconducting and their role might be to screen the Coulomb repulsion.…”

Section: B Experimental Feasibility Of the Surface Superconductivity ...mentioning

confidence: 99%

Quantum critical point in the superconducting transition on the surface of a topological insulator

Rosenstein

Shapiro

et al. 2014

Phys. Rev. B

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Pairing in the Weyl semi -metal appearing on the surface of topological insulator is considered. It is shown that due to an "ultra-relativistic" dispersion relation there is a quantum critical point governing the zero temperature transition to a superconducting state. Starting from the microscopic Hamiltonian with local attraction, we calculated using the Gor'kov equations, the phase diagram of the superconducting transition at arbitrary chemical potential, its magnetic properties and critical exponents close to the quantum critical point. The Ginzburg -Landau effective theory is derived for small chemical potential allowing to consider effects of spatial dependence of order parameters in magnetic field. The GL equations are very different from the conventional ones reflecting the chiral universality class of the quantum phase transition. The order parameter distribution of a single vortex is found to be different as well. The magnetization near the upper critical field is found to be quadratic, not linear as usual. We discuss the application of these results to recent experiments in which surface superconductivity was found that some 3D topological insulators and estimate feasibility of the phonon pairing.

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“…Moreover, it was found in graphene (which has an identical Coulomb interaction) that although the semimetal does not screen [44], the effects of the Coulomb coupling are surprisingly small, even in the leading order in perturbation theory. Superconductivity was observed in these systems, which, however, had to be doped either in the bulk or on the surface [81][82][83][84] by supplying Cu or by applying pressure [85]. It is not yet clear whether the observed superconductivity is a bulk or a surface effect.…”

Section: Experimental Feasibility Of Observing Quantum Phase Transitionsmentioning

confidence: 99%

Chiral universality class of normal-superconducting and exciton condensation transitions on surface of topological insulator

Rosenstein

Shapiro

et al. 2015

Front. Phys.

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New two-dimensional systems such as the surfaces of topological insulators (TIs) and graphene offer the possibility of experimentally investigating situations considered exotic just a decade ago. These situations include the quantum phase transition of the chiral type in electronic systems with a relativistic spectrum. Phonon-mediated (conventional) pairing in the Dirac semimetal appearing on the surface of a TI causes a transition into a chiral superconducting state, and exciton condensation in these gapless systems has long been envisioned in the physics of narrow-band semiconductors. Starting from the microscopic Dirac Hamiltonian with local attraction or repulsion, the BardeenCooper-Schrieffer type of Gaussian approximation is developed in the framework of functional integrals. It is shown that owing to an ultrarelativistic dispersion relation, there is a quantum critical point governing the zero-temperature transition to a superconducting state or the exciton condensed state. Quantum transitions having critical exponents differ greatly from conventional ones and belong to the chiral universality class. We discuss the application of these results to recent experiments in which surface superconductivity was found in TIs and estimate the feasibility of phonon pairing.

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Superconductivity in textured Bi clusters/Bi2Te3 films

Cited by 13 publications

References 40 publications

Electron-phonon coupling and surface Debye temperature of Bi2Te3 (111) from helium atom scattering

Electron-phonon coupling and surface Debye temperature of Bi2Te3 (111) from helium atom scattering

Quantum critical point in the superconducting transition on the surface of a topological insulator

Chiral universality class of normal-superconducting and exciton condensation transitions on surface of topological insulator

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