Strong magnetic frustration and anti-site disorder causing spin-glass behavior in honeycomb Li2RhO3

TL;DR

This study investigates the magnetic properties of Li2RhO3, revealing that magnetic frustration and anti-site disorder lead to spin-glass behavior, with a predicted dimerized ground state in pristine crystals and disorder-induced spin-glass phase.

Contribution

It provides the first electronic-structure calculations explaining the spin-glass behavior in Li2RhO3 due to magnetic frustration and anti-site disorder.

Findings

Pristine crystals have a dimerized ground state similar to Li2IrO3.

Anti-site disorder induces a superposition of nearly degenerate configurations.

Spin-glass phase arises from magnetic frustration and disorder.

Abstract

With large spin-orbit coupling, the $t_{2g}^5$ electron configuration in $d$-metal oxides is prone to highly anisotropic exchange interactions and exotic magnetic properties. In $5d^5$ iridates, given the existing variety of crystal structures, the magnetic anisotropy can be tuned from antisymmetric to symmetric Kitaev-type, with interaction strengths that outsize the isotropic terms. By many-body electronic-structure calculations we here address the nature of the magnetic exchange and the intriguing spin-glass behavior of Li$_2$RhO$_3$, a $4d^5$ honeycomb oxide. For pristine crystals without Rh-Li site inversion, we predict a dimerized ground state as in the isostructural $5d^5$ iridate Li$_2$IrO$_3$, with triplet spin dimers effectively placed on a frustrated triangular lattice. With Rh-Li anti-site disorder, we explain the observed spin-glass phase as a superposition of different, nearly degenerate symmetry-broken configurations.