Nature of the Antiferromagnetic Order in GdCu$_2$

TL;DR

This study used neutron diffraction to reveal that GdCu₂ exhibits an incommensurate antiferromagnetic order with a temperature-dependent wave vector, differing from previously reported commensurate structures.

Contribution

It provides the first detailed neutron diffraction analysis showing incommensurate magnetic order in GdCu₂ and its temperature dependence.

Findings

Magnetic peaks at incommensurate positions with q=(0.678, 1, 0).

Deviation from previously reported commensurate order.

Temperature-dependent shift of the magnetic peaks.

Abstract

A magnetic order in orthorhombic GdCu$_2$ was investigated via a single crystal neutron diffraction with thermal neutron. Magnetic peaks were observed at incommensurate positions described by the ordering vector $q$=(${\delta}$,~1,~0) with ${\delta}$=0.678 at 4.6~K. This ordering vector is close to the commensurate one with $q_{\rm c}$=(2/3,~1,~0) reported earlier, but clearly deviates. The incommensurate nature of the magnetic order in GdCu$_2$ is further corroborated by the peak shift with temperature below $T_{\rm N}$.