Topological multicomponent-pairing superconductivity in twisted bilayer cuprates

TL;DR

This paper explores a topologically nontrivial multicomponent superconducting state in twisted bilayer cuprates, combining theoretical analysis and microscopic modeling to demonstrate its stability and topological properties.

Contribution

It introduces a new topological three-component pairing state in twisted bilayer cuprates, supported by Ginzburg--Landau and mean-field calculations.

Findings

The three-component pairing state can be topologically nontrivial.

Such a state remains stable over a wide parameter range.

Twisted bilayer cuprates can host chiral, topological superconductivity despite sizable s-wave components.

Abstract

We investigate the emergence of a multicomponent superconducting state in twisted bilayer cuprates, characterized by the order parameter $s+d_1 e^{i\phi_1}+d_2 e^{i\phi_2}$, where $s=s_1+s_2$ denotes the symmetric combination of the layer-resolved $s$-wave components, and $s_i$ and $d_i$ ($i=1,2$) represent the $s$-wave and $d$-wave pairings associated with the individual layers. In particular, when $\phi_1-\phi_2\neq 0,\pi$, this three-component pairing state is topologically nontrivial. By combining Ginzburg--Landau analysis with self-consistent mean-field calculations based on a microscopic model, we show that such a topological three-component pairing state can be stabilized over a substantial parameter regime. Our results indicate that twisted bilayer cuprates can remain chiral and topological even in the presence of a sizable $s$-wave pairing component.