# Electron-Nuclear Hyperfine Coupling in Quantum Kagome Antiferromagnets from First-Principles Calculation and a Reflection of the Defect Effect

## TL;DR

This paper uses first-principles calculations to analyze hyperfine coupling in quantum kagome antiferromagnets, helping interpret NMR data affected by defects and advancing understanding of quantum spin liquids.

## Contribution

It introduces a computational approach to accurately predict hyperfine couplings and assess defect effects in kagome antiferromagnets, aiding NMR data analysis.

## Key findings

- Hyperfine coupling strengths can be reliably calculated from first principles.
- Defects significantly influence hyperfine interactions at nuclear sites.
- The method bridges the gap between theoretical predictions and experimental NMR data.

## Abstract

The discovery of ideal spin-1/2 kagome antiferromagnets Herbertsmithite and Zn-doped Barlowite represents a breakthrough in the quest for quantum spin liquids (QSLs), and nuclear magnetic resonance (NMR) spectroscopy plays a prominent role in revealing the quantum paramagnetism in these compounds. However, interpretation of NMR data that is often masked by defects can be controversial. Here, we show that the most significant interaction strength for NMR, i.e. the hyperfine coupling (HFC) strength, can be reasonably reproduced by first-principles calculations for these proposed QSLs. Applying this method to a supercell containing Cu-Zn defects enables us to map out the variation and distribution of HFC at different nuclear sites. This predictive power is expected to bridge the missing link in the analysis of the low-temperature NMR data.