Magnetic correlations in the semimetallic hyper-kagome iridate Na3Ir3O8

TL;DR

This study uses $^{23}$Na NMR to investigate the magnetic properties of Na$_3$Ir$_3$O$_8$, revealing semimetallic behavior with persistent antiferromagnetic fluctuations and short-range correlations, suggesting complex electron interactions.

Contribution

First microscopic NMR analysis of Na$_3$Ir$_3$O$_8$ showing its semimetallic nature and magnetic fluctuations, extending understanding of hyperkagome iridates.

Findings

Susceptibility indicates semimetal behavior with correlated electronic bands.

Antiferromagnetic fluctuations from the parent compound persist.

Spin dynamics suggest 120° excitation modes with short-range correlations.

Abstract

We present a microscopic study of a doped quantum spin liquid candidate, the hyperkagome Na$_3$Ir$_3$O$_8$ compound by using $^{23}$Na NMR. We determine the intrinsic behavior of the uniform \textbf{q} $ = 0$ susceptibility via shift measurements and the dynamical response by probing the spin-lattice relaxation rate. Throughout the studied temperature range, the susceptibility is consistent with a semimetal behavior, though with electronic bands substantially modified by correlations. Remarkably, the antiferromagnetic fluctuations present in the insulating parent compound Na$_4$Ir$_3$O$_8$ survive in the studied compound. The spin dynamics are consistent with 120$^o$ excitations modes displaying short-range correlations.