Josephson effects in twisted cuprate bilayers

Tummuru, Tarun; Plugge, Stephan; Franz, Marcel

doi:10.1103/physrevb.105.064501

Cited by 42 publications

(34 citation statements)

References 38 publications

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“…Their physics is therefore similar to that of a twisted bilayer [21,35,36]. Nevertheless, in view of the estimates for the tunneling strength g ∼ 5 − 10meV inferred from recent transport studies [24,29,30], such a renormalization might help stabilize T -broken superconductivity. In contrast, the problem posed by CT multilayers cannot be simplified in this way.…”

Section: Discussionmentioning

confidence: 80%

“…Transport measurements find that close to 45 • twist angle, the interlayer Josephson current is dominated by its second harmonic, which signals co-tunneling of Cooper pairs [24]. While indicative of a non-trivial phase difference between the two superconducting layers, and hence T breaking, this does not directly reveal the topological nature of the state [29,30]. Along similar lines, Ref.…”

Section: Introductionmentioning

confidence: 86%

“…The gap scales as e 1/U D(0) for small U, where D(0) = g/πv F v ∆ ∼ g/2π∆ is the density of states at zero energy at the QBT (see Appendix D). The induced gap is thus exponentially small in both the interaction U and the effective tunneling strength g/∆, which explains the numerical difficultly in stabilizing this phase, unless one uses an unphysically large U that is on verge of destabilizing the primary d-wave order [30].…”

Section: B Quadratic Band Touchingmentioning

confidence: 99%

See 2 more Smart Citations

Twisted multilayer nodal superconductors

Tummuru,

Lantagne-Hurtubise,

Franz

2022

Preprint

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Twisted bilayers of nodal superconductors were recently proposed as a promising platform to host superconducting phases that spontaneously break time-reversal symmetry. Here we extend this analysis to twisted multilayers, focusing on two high-symmetry stackings with alternating (±θ) and constant (θ) twist angles. In analogy to alternating-twist multilayer graphene, the former can be mapped to twisted bilayers with renormalized interlayer couplings, along with a remnant gapless monolayer when the number of layers L is odd. In contrast, the latter exhibits physics beyond twisted bilayers, including the occurrence of 'magic angles' characterized by cubic band crossings when L mod 4 = 3. Owing to their power-law divergent density of states, such multilayers are highly susceptible to secondary instabilities. Within a BCS mean-field theory, defined in the continuum and on a lattice, we find that both stackings host chiral topological superconductivity in extended regions of their phase diagrams.

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Section: Discussionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 86%

Section: B Quadratic Band Touchingmentioning

confidence: 99%

See 1 more Smart Citation

Twisted multilayer nodal superconductors

Tummuru,

Lantagne-Hurtubise,

Franz

2022

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Transport measurements find that close to 45 • twist angle, the interlayer Josephson current is dominated by its second harmonic, which signals cotunneling of Cooper pairs [24]. While indicative of a nontrivial phase difference between the two superconducting layers, and hence T breaking, this does not directly reveal the topological nature of the state [29,30]. Along similar lines, Ref.…”

Section: Introductionmentioning

confidence: 85%

“…The gap is thus exponentially small in both the interaction U and the effective tunneling strength g/ . This underlies the numerical difficultly in stabilizing this phase, unless using an unphysically large U that is on the verge of destabilizing the primary d-wave order [30].…”

Section: B Quadratic Band Touchingmentioning

confidence: 99%

Twisted multilayer nodal superconductors

2022

Self Cite

View full text Add to dashboard Cite

Twisted bilayers of nodal superconductors were recently proposed as a promising platform to host superconducting phases that spontaneously break time-reversal symmetry. Here we extend this analysis to twisted multilayers, focusing on two high-symmetry stackings with alternating (±θ) and constant (θ) twist angles. In analogy to alternating-twist multilayer graphene, the former can be mapped to twisted bilayers with renormalized interlayer couplings, along with a remnant gapless monolayer when the number of layers L is odd. In contrast, the latter exhibits physics beyond twisted bilayers, including the occurrence of "magic angles" characterized by cubic band crossings when L mod 4 = 3. Due to their power-law divergent density of states, such multilayers are highly susceptible to secondary instabilities. Within a BCS mean-field theory, defined in the continuum and on a lattice, we find that both stackings host chiral topological superconductivity in extended regions of their phase diagrams.

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Encapsulating High‐Temperature Superconducting Twisted van der Waals Heterostructures Blocks Detrimental Effects of Disorder

et al. 2023

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High‐temperature cuprate superconductors based van der Waals (vdW) heterostructures hold high technological promise. One of the obstacles hindering their progress is the detrimental effect of disorder on the properties of the vdW‐devices‐based Josephson junctions (JJs). Here, a new method of fabricating twisted vdW heterostructures made of Bi2Sr2CuCa2O8+δ, crucially improving the JJ characteristics and pushing them up to those of the intrinsic JJs in bulk samples, is reported. The method combines cryogenic stacking using a solvent‐free stencil mask technique and covering the interface by insulating hexagonal boron nitride crystals. Despite the high‐vacuum condition down to 10−6 mbar in the evaporation chamber, the interface appears to be protected from water molecules during the in situ metal deposition only when fully encapsulated. Comparing the current–voltage curves of encapsulated and unencapsulated interfaces, it is revealed that the encapsulated interfaces’ characteristics are crucially improved, so that the corresponding JJs demonstrate high critical currents and sharpness of the superconducting transition comparable to those of the intrinsic JJs. Finally, it is shown that the encapsulated heterostructures are more stable over time.

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Josephson effects in twisted cuprate bilayers

Cited by 42 publications

References 38 publications

Twisted multilayer nodal superconductors

Twisted multilayer nodal superconductors

Twisted multilayer nodal superconductors

Encapsulating High‐Temperature Superconducting Twisted van der Waals Heterostructures Blocks Detrimental Effects of Disorder

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