Making chiral topological superconductors from nontopological superconductors through large angle twists

The material realization of the intrinsic chiral topological superconductivity (TSC) is still a big challenge in modern condensed-matter physics. In this paper, we propose a general scheme to make chiral TSCs from nontopological superconductivities (SCs) through the newly developed ``twistronics'' technique. Suppose we have a ${D}_n$-symmetric monolayer carrying nontopological SC with pairing angular momentum $L=n/2$. Here we propose that by stacking two such monolayers with the largest twist angle, the interlay Josephson coupling can drive chiral TSC with the same $L$ in the system. An argument based on the universal Ginzburg-Landau theory is provided to understand this proposal. One known example which fits our proposal is the $d+id$ chiral TSC in the ${45}^{\ensuremath{\circ}}$-twisted bilayer cuprates. Here, we demonstrate the application of our proposal to a new example, i.e., the $f+if$ chiral TSC obtained by twisting two properly doped honeycomb-Hubbard-model monolayers by the angle ${30}^{\ensuremath{\circ}}$. This example is related to the newly synthesized ${30}^{\ensuremath{\circ}}$-twisted bilayer graphene.