Magnetic structure of divalent europium compound EuGa$_4$ studied by single crystal time-of-flight neutron diffraction

TL;DR

This study used single-crystal neutron diffraction to determine the magnetic structure of EuGa4, revealing a well-localized Eu2+ magnetic moment within the basal plane despite high neutron absorption.

Contribution

First detailed magnetic structure determination of EuGa4 using TOF neutron diffraction without isotope enrichment, demonstrating the technique's effectiveness for high-absorption materials.

Findings

EuGa4 has a magnetic ordering vector q=(0,0,0).

Eu magnetic moments are nearly full and lie within the basal plane.

The magnetic reflection intensity follows a squared Brillouin function for S=7/2.

Abstract

The magnetic structure of the intermetallic compound EuGa$_4$ was investigated using single-crystal neutron diffraction with the time-of-flight (TOF) Laue technique on the new diffractometer SENJU at MLF of J-PARC. In spite of high neutron absorption of Eu, a vast number of diffraction spots were observed without isotope enrichment. The magnetic reflections were appeared at the positions with the diffraction indices of $h+k+l{\neq}2n$ below 16 K, indicating that the ordering vector is ${\bf q}=(0~0~0)$. Continuous evolution of magnetic reflection intensity below $T_{\rm N}$ follows a squared Brillouin function for $S$=7/2. By adopting a wavelength-dependent absorption collection, the magnetic structure of EuGa$_4$ was revealed that a nearly full magnetic moment of 6.4$~{\mu}_{\rm B}$ of Eu lies within the basal plane of the lattice. The present study reveals a well-localized divalent Eu magnetism in EuGa$_4$ and demonstrates a high ability of SENJU to investigate materials with high neutron absorption.