Electronic and magnetic properties of a quasi-one-dimensional spin chain system, Sr$_{3}$NiRhO$_{6}$

TL;DR

This study uses ab initio calculations to explore the electronic and magnetic properties of Sr$_3$NiRhO$_6$, revealing it as a Mott insulator with potential spin-polarized conduction, emphasizing the importance of electron correlations.

Contribution

First detailed ab initio analysis showing Sr$_3$NiRhO$_6$ as a Mott insulator with magnetic ordering and spin-polarized conduction potential.

Findings

Ni and Rh have finite magnetic moments and are antiferromagnetically coupled.

Electron correlations are essential to reproduce the insulating behavior.

The system exhibits spin-dependent energy gaps, indicating possible spin-polarized conduction.

Abstract

We investigate the electronic structure of Sr$_3$NiRhO$_6$, a quasi-one-dimensional spin chain system using \emph{ab initio} band structure calculations. Spin polarized calculations within GGA reveal that Ni and Rh have finite moments and they are antiferromagnetically coupled along the chain axis in the ground state. While these results obtained within the local spin density approximations provide remarkable representation of the magnetic phase, the experimentally observed insulating behavior could not be captured within this method. GGA+$U$ calculations show that opening up of an insulating gap requires on-site Coulomb interaction among the Rh 4$d$ electrons, $U_{dd}^{Rh}$ $\approx$ 2.5 eV and the correlation among Ni 3$d$ electrons, $U_{dd}^{Ni}$ $\approx$ 4.5 eV suggesting this system to be a Mott insulator. Electron correlation among $d$ electrons leads to significant enhancement of the O 2$p$ character in the energy bands in the vicinity of the Fermi level and the $d$ bands appear at lower energies. Energy gap in the up spin density of states appears to be significantly small ($\sim$ 0.12 eV) while it is $>$ 2 eV in the down spin density of states suggesting possibility of spin polarized conduction in the semiconducting phase.