153Eu and 69,71Ga Zero-Field NMR Study of Antiferromagnetic State in EuGa4

TL;DR

This study uses zero-field NMR to investigate the antiferromagnetic state of EuGa4, revealing detailed magnetic and quadrupole properties and their temperature dependence, providing insights into the magnetic structure of the material.

Contribution

First zero-field NMR observation of EuGa4's antiferromagnetic state, with detailed analysis of magnetic moments and quadrupole interactions using spectral simulations.

Findings

Eu$^{153}$ NMR signal with quadrupole splitting observed

Internal magnetic field and quadrupole frequency estimated from spectra

Temperature dependence of internal field matches Brillouin function for J=S=7/2

Abstract

We report $^{153}$Eu and $^{69,71}$Ga NMR under a zero magnetic field on the antiferromagnetic state of EuGa$_{4}$ with $T_{\rm{N}}\approx 16$ K. We have successfully observed a $^{153}$Eu zero-field NMR signal with well-resolved nuclear quadrupole splitting in the antiferromagnetic state of EuGa$_{4}$. $^{69,71}$Ga zero-field NMR spectra were also observed below $T_{\rm{N}}$. The internal field and nuclear quadrupole frequency are estimated from a simulation of the spectra by the exact diagonalization of the nuclear spin Hamiltonian matrix. The asymmetrically split zero-field NMR spectra were explained by considering a configuration of the magnetic moments of Eu$^{2+}$ lying in the basal $ab$-plane. The temperature dependence of the internal field, which is proportional to the sublattice magnetization, can be explained by the Brillouin function with $J=S=7/2$