Decomposition of multilayer superconductivity with interlayer pairing

TL;DR

This paper demonstrates that multilayer superconductors with interlayer pairing can be effectively decomposed into weakly-coupled bilayer and trilayer blocks, revealing unique properties like order parameter modulation and short coherence length.

Contribution

It provides a theoretical framework showing the natural decomposition of multilayer interlayer pairing superconductivity into simpler bilayer and trilayer units.

Findings

Superconductivity decomposes into weakly-coupled bilayer/trilayer blocks.

Strong order parameter modulation along the z-axis.

Short coherence length perpendicular to layers.

Abstract

We prove that multilayer superconductivity with interlayer pairing may naturally decompose into a series of weakly-coupled bilayer and trilayer superconducting blocks in order to minimize its total free energy. Our work is motivated by the recent proposal of interlayer pairing induced by the interlayer superexchange interaction of nearly half-filled $d_{z^2}$ orbitals in the bilayer and trilayer nickelate superconductors. We explore general properties of interlayer pairing superconductivity and perform systematic Ginzburg-Landau analyses of an effective multilayer model. For real materials, our results imply strong superconducting order parameter modulation and short coherence length along the $z$-axis (perpendicular to the layers). This reveals a unique feature of multilayer superconductivity with interlayer pairing and provides a basic framework for future experimental and theoretical investigations.