Anisotropic magnetic diffuse scattering in an easy-plane type antiferromagnet ErNi$_{2}$Ge$_{2}$

TL;DR

This study uses neutron scattering to reveal anisotropic magnetic diffuse scattering in ErNi$_{2}$Ge$_{2}$, showing coexistence of short-range and long-range magnetic orders with a helical structure.

Contribution

It provides detailed insights into the anisotropic diffuse scattering and magnetic structure of ErNi$_{2}$Ge$_{2}$, highlighting the coexistence of short- and long-range magnetic orders.

Findings

Magnetic moments lie in the ab-plane.

Short-range order coexists with long-range order.

Diffuse scattering is anisotropic, indicating one-dimensional helices.

Abstract

We report on neutron scattering studies of a rare earth intermetallic compound ErNi$_{2}$Ge$_{2}$. Polarized neutron scattering experiments revealed that the magnetic ordered moment ${\bm m}$ lies in ab-plane. Taking account of a lack of the third higher harmonic reflection, ErNi$_{2}$Ge$_{2}$ is considered to have a helical magnetic structure. The magnetic scattering profiles along the $[100]^{\ast}$- and the $[110]^{\ast}$-directions are well described by the sum of Gaussian and modified-Lorentzian terms, even far below $T_{\scriptsize N}$, indicating that short-range orders coexist with a long-range order. Interestingly, the modified-Lorentzian-type diffuse scattering is not present in the profiles along the $[001]^{\ast}$-direction. The anisotropy of the diffuse scattering suggests that the short-range-order consists of one dimensional long-range helices along the c-axis.