# Magnetic interactions in the tripod-kagome antiferromagnet Mg$_{2}$Gd$_{3}$Sb$_{3}$O$_{14}$ probed by static magnetometry and high-field ESR spectroscopy

## TL;DR

This study investigates the magnetic interactions in Mg$_{2}$Gd$_{3}$Sb$_{3}$O$_{14}$, revealing weak antiferromagnetic coupling, long-range order at 1.7 K, and signs of spin frustration through magnetometry and ESR spectroscopy.

## Contribution

First detailed experimental analysis of magnetic interactions and spin frustration in the newly identified tripod-kagome antiferromagnet Mg$_{2}$Gd$_{3}$Sb$_{3}$O$_{14}$ using magnetometry and ESR.

## Key findings

- Gd$^{3+}$ spins are coupled by weak AFM exchange ($|J| \\approx 0.3$ K).
- Long-range AFM order observed at 1.7 K.
- ESR line broadening indicates spin correlations above the ordering temperature.

## Abstract

We report an experimental study of the static magnetization $M(H,T)$ and high-field electron spin resonance (ESR) of polycrystalline \MgGd, a representative member of the newly discovered class of the so-called tripod-kagome antiferromagnets where the isotropic Gd$^{3+}$ spins ($S = 7/2$) form a two-dimensional kagome spin-frustrated lattice. It follows from the analysis of the low-$T$ $M(H)$-curves that the Gd$^{3+}$ spins are coupled by a small isotropic antiferromagnetic (AFM) exchange interaction $|J| \approx$ 0.3\,K. The $M(H,T)$-dependences measured down to 0.5\,K evidence a long-range AFM order at $T_{\text{N}} = 1.7$\,K and its rapid suppression at higher fields $\geq 4$\,T. ESR spectra measured in fields up to 15\,T are analyzed considering possible effects of demagnetizing fields, single-ion anisotropy and spin-spin correlations. While the demagnetization effects due to a large sample magnetization in high fields and its shape anisotropy become relevant at low temperatures, the broadening of the ESR line commencing already at $T\lesssim 30$\,K may indicate the onset of the spin-spin correlations far above the ordering temperature due to the geometrical spin frustration in this compound.