Strongly Correlated Inhomogeneous High-Temperature Superconductors  

Licentiate thesis, 2025

Since its discovery, superconductivity has received significant attention, with renewed interest following the discovery of high-temperature superconductors (HTSCs) such as cuprates. The t–J model, combined with the Gutzwiller approximation, has been used to study HTSCs. While much research has focused on homogeneous systems, less attention has been given inhomogeneous ones - especially the possible coexistence of superconductivity and antiferromagnetism in them. The coexistence could be of interest for applications within superconducting spintronics.
The focus of the present thesis is [110] edges of HTSCs. It is shown that these edges attract quasiparticles, increasing the local occupation and thereby strengthening local correlation, which in turn reduces the weight of the zero-energy Andreev bound states typically present at [110] edges. Furthermore, the s-wave order parameter, predicted in some models to form at the edge, is here seen to vanish or be suppressed. Finally, it is demonstrated that the charging of the edges enables antiferromagnetic order to emerge at the edges at higher average dopings than in homogeneous systems.