Long-range magnetic order in CeRu2Al10 evidenced by muSR and neutron diffraction

TL;DR

This study uses neutron diffraction and muSR to confirm that CeRu2Al10 exhibits long-range magnetic order below 27K, with a collinear antiferromagnetic structure, and suggests a possible second transition near 12K.

Contribution

The paper provides definitive evidence of magnetic ordering in CeRu2Al10 and clarifies its magnetic structure using combined neutron and muSR techniques.

Findings

Magnetic order sets in below 27K with a propagation vector (1,0,0).

Ce moments align antiferromagnetically along the c-axis.

An anomaly around 12K suggests a potential second transition.

Abstract

The low temperature state of CeRu2Al10 has been studied by neutron powder diffraction and muon spin relaxation (muSR). By combining both techniques, we prove that the transition occurring below T*~27K, which has been the subject of considerable debate, is unambiguously magnetic due to the ordering of the Ce sublattice. The magnetic structure with propagation vector k=(1,0,0) involves collinear antiferromagnetic alignment of the Ce moments along the c-axis of the Cmcm space group with a reduced moment of 0.34(2)mu_B. No structural changes within the resolution limit have been detected below the transition temperature. However, the temperature dependence of the magnetic Bragg peaks and the muon precession frequency show an anomaly around T2~12 K indicating a possible second transition.