# Charge transfer and metallicity in LaNiO$_3$/LaMnO$_3$ superlattices

## TL;DR

This study uses density functional theory with +U correction to analyze charge transfer and metallicity in LaNiO₃/LaMnO₃ superlattices, revealing moderate charge transfer and metallic behavior, contrasting with experimental insulating observations.

## Contribution

It demonstrates that band parameters are transferable from bulk to superlattice, except for d-level energies, and suggests defects may explain experimental insulating behavior.

## Key findings

- Charge transfer from Mn to Ni is moderate, indicating metallicity.
- Rocksalt structure is insulating with large Mn-Ni charge transfer.
- Defects may cause insulating behavior in short-period superlattices.

## Abstract

Motivated by recent experiments, we use the $+U$ extension of the generalized gradient approximation to density functional theory to study superlattices composed of alternating layers of LaNiO$_3$ and LaMnO$_3$. For comparison we also study a rocksalt ((111) double perovskite) structure and bulk LaNiO$_3$ and LaMnO$_3$. A Wannier function analysis indicates that band parameters are transferable from bulk to superlattice situations with the exception of the transition metal d-level energy, which has a contribution from the change in d-shell occupancy. The charge transfer from Mn to Ni is found to be moderate in the superlattice, indicating metallic behavior, in contrast to the insulating behavior found in recent experiments, while the rocksalt structure is found to be insulating with a large Mn-Ni charge transfer. We suggest a high density of cation antisite defects may account for the insulating behavior experimentally observed in short-period superlattices.