Odd-frequency superconductivity induced in topological insulators with and without hexagonal warping

Vasenko, A. S.; Golubov, A. A.; Silkin, V. M.; Chulkov, Eugene V.

doi:10.1088/1361-648x/aa75c3

Cited by 10 publications

(11 citation statements)

References 81 publications

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“…Using the relatioň G 0 (k, ω n ) −1 = iω n −Ȟ 0 (k), we reach Eq. (38). For representing the impurities self-energy, the momentum summation of the Green functions is necessary,…”

Section: Discussionmentioning

confidence: 99%

Green's-function theory of dirty two-band superconductivity

Asano

Golubov

2018

Phys. Rev. B

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We study the effects of random nonmagnetic impurities on the superconducting transition temperature Tc in a two-band superconductor, where we assume an equal-time spin-singlet s-wave pair potential in each conduction band and the hybridization between the two bands as well as the band asymmetry. In the clean limit, the phase of hybridization determines the stability of two states: called s++ and s+−. The interband impurity scatterings decrease Tc of the two states exactly in the same manner when time-reversal symmetry is preserved in the Hamiltonian. We find that a superconductor with larger hybridization shows more moderate suppression of Tc. This effect can be explained by the presence of odd-frequency Cooper pairs which are generated by the band hybridization in the clean limit and are broken by impurities.

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“…Using the relatioň G 0 (k, ω n ) −1 = iω n −Ȟ 0 (k), we reach Eq. (38). For representing the impurities self-energy, the momentum summation of the Green functions is necessary,…”

Section: Discussionmentioning

confidence: 99%

Green's-function theory of dirty two-band superconductivity

Asano

Golubov

2018

Phys. Rev. B

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“…In the case of a spin-triplet superconductor, the anomalous Green function becomes (22). In equation (24), the hybridization generates the 0 r and 3 r components which belong to odd-frequency spin-triplet even-momentum-parity even-band-parity (OTEE) symmetry class [24][25][26][27]. We attribute this suppression of T c to the presence of odd-frequency pairs which typically have a detrimental effect on thermodynamic stability [25,28,29].…”

Section: Interband Pairing Ordermentioning

confidence: 99%

Dirty two-band superconductivity with interband pairing order

2018

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We study theoretically the effects of random nonmagnetic impurities on the superconducting transition temperature T c in a two-band superconductor characterized by an equal-time s-wave interband pairing order parameter. Because of the two-band degree of freedom, it is possible to define a spin-triplet s-wave pairing order parameter as well as a spin-singlet s-wave order parameter. The former belongs to odd-band-parity symmetry class, whereas the latter belongs to even-band-parity symmetry class. In a spin-singlet superconductor, T c is insensitive to the impurity concentration when we estimate the self-energy due to the random impurity potential within the Born approximation. On the other hand in a spin-triplet superconductor, T c decreases with the increase of the impurity concentration. We conclude that Cooper pairs belonging to odd-band-parity symmetry class are fragile under the random impurity potential even though they have s-wave pairing symmetry.

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“…Still, while the existence of such intrinsic odd‐ω order parameters remains an intriguing theoretical question, a great deal of progress has been made studying the emergence of odd‐ω pair correlations in systems with conventional equal‐time order parameters . This latter possibility relies on the conversion of intrinsic even‐ω superconducting correlations to odd‐ω correlations, with a number of proposals in the literature realizing such symmetry conversion through a variety of different mechanisms …”

Section: Introductionmentioning

confidence: 99%

The Role of Odd‐Frequency Pairing in Multiband Superconductors

2020

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Recent progress in the understanding of multiband superconductivity and its relationship to odd‐frequency pairing are reviewed herein. The discussion begins by reviewing the emergence of odd‐frequency pairing in a simple two‐band model, providing a brief pedagogical overview of the formalism. Several examples of multiband superconducting systems are examined, in each case describing both the origin of the band degree of freedom and the nature of the odd‐frequency pairing. Throughout, it is attempted to convey a unified picture of how odd‐frequency pairing emerges in these materials and propose that similar mechanisms are responsible for odd‐frequency pairing in several analogous systems: layered 2D heterostructures, double quantum dots, double nanowires, Josephson junctions, and systems described by isolated valleys in momentum space. In addition, experimental probes of odd‐frequency pairing in multiband systems are reviewed, focusing on hybridization gaps in the electronic density of states, paramagnetic Meissner effect, and Kerr effect.

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Odd-frequency superconductivity induced in topological insulators with and without hexagonal warping

Cited by 10 publications

References 81 publications

Green's-function theory of dirty two-band superconductivity

Green's-function theory of dirty two-band superconductivity

Dirty two-band superconductivity with interband pairing order

The Role of Odd‐Frequency Pairing in Multiband Superconductors

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