Coexistence of magnetism and superconductivity in a t-J bilayer

TL;DR

This study uses variational Monte Carlo to explore how antiferromagnetism and d-wave superconductivity coexist and compete in a bilayer t-J model, revealing doping-dependent behaviors influenced by interlayer couplings.

Contribution

It demonstrates the conditions under which magnetic and superconducting phases coexist and how interlayer couplings affect these correlations across doping levels.

Findings

Coexistence of antiferromagnetism and superconductivity in underdoped regime.

Interplanar hopping reduces magnetic correlations away from half filling.

Overdoped regime shows stabilization of superconductivity with interlayer exchange.

Abstract

We investigate coexistence of antiferromagnetic and superconducting correlations in bilayered materials using a two-dimensional t-J model with couplings across the layers using variational Monte Carlo calculations. It is found that the underdoped regime supports a coexisting phase, beyond which the (d-wave) superconducting state becomes stable. Further, the effects of interplanar coupling parameters on the magnetic and superconducting correlations as a function of hole doping are studied in details. The magnetic correlations are found to diminish with increasing interplanar hopping away from half filling, while the exchange across the layers strengthens interplanar antiferromagnetic correlations both at and away from half filling. The superconducting correlations show more interesting features where larger interplanar hopping considerably reduces planar correlations at optimal doping, while an opposite behaviour, i.e. stabilisation of the superconducting state is realised in the overdoped regime, with the interplanar exchange all the while playing a dormant role.