Nuclear resonant scattering from 193Ir as a probe of the electronic and magnetic properties of iridates

TL;DR

This paper demonstrates the use of nuclear resonant scattering at 73 keV in 193Ir to probe the magnetic and electronic properties of iridates, revealing new insights into their anisotropic magnetism and hyperfine interactions.

Contribution

It introduces a novel high-energy x-ray method using 193Ir nuclear resonance to study correlated materials containing iridium, enabling detailed magnetic and electronic analysis without isotopic enrichment.

Findings

Detection of unexpected out-of-plane magnetic hyperfine components in Sr2IrO4

Observation of non-zero electric field gradients indicating strong spin-orbit coupling

High sensitivity to hyperfine field changes due to multipolarity mixing

Abstract

The high brilliance of the modern synchrotron radiation sources facilitates experiments with high energy x-rays. In this Letter we report on Nuclear Resonance Scattering at the 73 keV nuclear level in 193Ir. The transitions between the hyperfine split levels show an exceptionally large E2/M1 multi-polarity mixing ratio combined with an increased sensitivity to certain changes in the hyperfine field direction compared to non-mixing transitions. The method opens a new way for probing local magnetic and electronic properties of correlated materials containing iridium and provides novel insights into their anisotropic magnetism. In particular, unexpected out-of-plane components of magnetic hyperfine fields and non-zero electric field gradients in Sr2IrO4 have been detected and attributed to the presence of strong spin-orbit interaction. Due to the high, 62% natural abundance of the 193Ir isotope, no isotopic enrichment of the samples is required, qualifying the method for a broad range of applications.