Sr$_3$LiIrO$_6$: a potential quantum spin liquid candidate in the one dimensional $d^4$ iridate family

TL;DR

This study investigates Sr$_3$LiIrO$_6$, revealing it as a potential quantum spin liquid candidate due to its frustrated magnetic interactions and absence of magnetic order down to very low temperatures.

Contribution

The paper provides the first detailed experimental and theoretical analysis of Sr$_3$LiIrO$_6$, demonstrating its magnetic frustration and potential as a quantum spin liquid in a one-dimensional $d^4$ iridate.

Findings

Ir$^{5+}$ moments are present despite expectations of nonmagnetic state

No magnetic ordering observed down to 2 K due to frustration

Geometric frustration arises from interchain superexchange interactions

Abstract

Spin-orbit coupling (SOC) offers a large variety of novel and extraordinary magnetic and electronic properties in otherwise `ordinary pool' of heavy ion oxides. Here we present a detailed study on an apparently isolated hexagonal 2$H$ spin-chain $d^4$ iridate Sr$_3$LiIrO$_6$ (SLIO) with geometric frustration. Our structural studies clearly reveal perfect Li-Ir chemical order in this compound. Our combined experimental and {\it ab-initio} electronic structure investigations establish a magnetic ground state with finite Ir$^{5+}$ magnetic moments in this compound, contrary to the anticipated nonmagnetic $J$=0 state. Furthermore, the dc magnetic susceptibility ($\chi$), heat capacity ($C_p$) and spin-polarized density functional theory (DFT) studies unravel that despite having noticeable antiferromagnetic correlation among the Ir$^{5+}$ local moments, this SLIO system evades any kind of magnetic ordering down to at least 2 K due to geometrical frustration, arising from the comparable interchain Ir-O-O-Ir superexchange interaction strengths, hence promoting SLIO as a potential quantum spin liquid candidate.