Topological multicomponent superconductivity with sizable $s$-wave admixture in twisted bilayer cuprates

Abstract

We investigate multicomponent superconductivity in twisted bilayer cuprates with order parameter $s+d_1 e^{i\phi_1}+d_2 e^{i\phi_2}$, where $s=s_1+s_2$ is the symmetric layer-resolved $s$-wave component and $d_i$ denotes the $d$-wave pairing in layer $i$. When $\phi_1-\phi_2\neq 0,\pi$, this three-component state breaks time-reversal and $C_4$ rotational symmetries and is topologically nontrivial. Combining Ginzburg--Landau analysis with self-consistent microscopic mean-field calculations, we show that this topological state is stabilized over a broad parameter regime. We further identify nematic Kerr anisotropy as a smoking-gun signature distinguishing it from $s+id$ and $d_1+e^{i\phi}d_2$ states. Our results show that a sizable $s$-wave component does not preclude chiral topological superconductivity, pointing to twisted cuprates as a more robust platform than previously appreciated.