Quasiperiodic criticality and spin-triplet superconductivity in superconductor-antiferromagnet moire patterns

TL;DR

This paper explores how quasiperiodic structures in superconductor-antiferromagnet systems can induce a localization-delocalization transition, leading to critical states and emergent spin-triplet superconductivity, offering new avenues for designing unconventional superconductors.

Contribution

It demonstrates the existence of a quasiperiodic critical point in superconductor-antiferromagnet systems and shows how residual interactions enhance spin-triplet superconductivity near this point.

Findings

Localization-delocalization transition as a function of coupling strength

Emergence of a robust quasiperiodic critical point for incommensurate potentials

Enhancement of spin-triplet superconductivity near the critical point

Abstract

Quasiperiodicity has long been known to be a potential platform to explore exotic phenomena, realizing an intricate middle point between ordered solids and disordered matter. In particular, quasiperiodic structures are promising playgrounds to engineer critical wavefunctions, a powerful starting point to engineer exotic correlated states. Here we show that systems hosting a quasiperiodic modulation of antiferromagnetism and spin-singlet superconductivity, as realized by atomic chains in twisted van der Waals materials, host a localization-delocalization transition as a function of the coupling strength. Associated with this transition, we demonstrate the emergence of a robust quasiperiodic critical point for arbitrary incommensurate potentials, that appears for generic relative weights of the spin-singlet superconductivity and antiferromagnetism. We show that the inclusion of residual electronic interactions leads to an emergent spin-triplet superconducting state, that gets dramatically enhanced at the vicinity of the quasiperiodic critical point. Our results put forward quasiperiodicity as a powerful knob to engineer robust superconducting states, providing an alternative pathway towards artificially designed unconventional superconductors.