Tunable Coupling of Two-Dimensional Superconductors in Bilayer SrTiO3 Heterostructures

TL;DR

This study demonstrates tunable interlayer coupling in bilayer SrTiO3 heterostructures, affecting superconducting properties and revealing a crossover from coupled to decoupled regimes.

Contribution

It introduces a method to control interlayer coupling in 2D superconductors via spacer layer tuning, revealing a crossover regime due to inter-sub-band interactions.

Findings

Tunable superconducting transition temperature with spacer layer variation

Observation of a crossover from coupled to decoupled superconducting layers

Inter-sub-band interactions influence the coupling regime

Abstract

Interlayer coupling effects between high mobility two-dimensional superconductors are studied in bilayer delta-doped SrTiO3 heterostructures. By tuning the undoped SrTiO3 spacer layer between the dopant planes, clear tunable coupling is demonstrated in the variation of the sheet carrier density, Hall mobility, superconducting transition temperature, and the temperature- and angle-dependences of the superconducting upper critical field. Systematic variation is found between one effective (merged) two-dimensional superconductor to two decoupled two-dimensional superconductors. In the intermediate coupled regime, a crossover is observed due to coupling arising from inter-sub-band interactions.