Competition between local potentials and attractive particle-particle interactions in superlattices

TL;DR

This study examines how different types of spatial modulations in superlattices influence their ground-state energy and charge distribution, revealing that potential modulations are more impactful than interaction modulations.

Contribution

It demonstrates that local potential modulations have a greater effect on superlattice properties than attractive interaction modulations, generalizing previous findings for repulsive interactions.

Findings

Potential modulations dominate over interaction modulations in shaping properties.

Results are consistent across attractive and repulsive interaction regimes.

Superlattice properties can be tuned via local potential variations.

Abstract

Naturally occuring or man-made systems displaying periodic spatial modulations of their properties on a nanoscale constitute superlattices. Such modulated structures are important both as prototypes of simple nanotechnological devices and as particular examples of emerging spatial inhomogeneity in interacting many-electron systems. Here we investigate the effect different types of modulation of the system parameters have on the ground-state energy and the charge-density distribution of the system. The superlattices are described by the inhomogeneous attractive Hubbard model, and the calculations are performed by density-functional and density-matrix renormalization group techniques. We find that modulations in local electric potentials are much more effective in shaping the system's properties than modulations in the attractive on-site interaction. This is the same conclusions we previously (Phys. Rev. B 71, 125130) obtained for repulsive interactions, suggesting that it is not an artifact of a specific state, but a general property of modulated structures.