Exactly solvable model of randomly coupled twisted superconducting bilayers

Abstract

Motivated by recent experiments on twisted junctions of cuprate superconductors (SCs), it was proposed [Yuan et al., Inhomogeneity-induced time-reversal symmetry breaking in cuprate twist junctions, Phys. Rev. B 108, L100505 (2023)] that at zero temperature, a random first order Josephson coupling J1(r)cosϕ generates an effective global second-order coupling, J2cos(2ϕ), with a sign that favors ϕ=±π/2, i.e., spontaneous breaking of time reversal symmetry (TRS). To obtain a more controlled understanding of the suggested disorder-induced-order mechanism, we construct an exactly solvable lattice mean-field model and prove that when the disorder-average J¯1=0, the model exhibits a TRS breaking phase for all temperatures below the SC transition, i.e., Tc=TTRSB, regardless of the specific form of disorder. In the presence of nonzero J¯1≠0, we show that the two transitions split linearly for small J¯1≪κ (where κ is the in-plane SC stiffness), and that TTRSB vanishes for J¯1>Jc where Jc=J12¯/κ in the weak disorder limit.

Source-reported materials — not catalogue approval

Similar papers