Magnetic properties of the noncentrosymmetric tetragonal antiferromagnet EuPtSi$_{3}$

TL;DR

This study investigates the magnetic behavior of EuPtSi₃, revealing antiferromagnetic order below 17 K, complex magnetic phases under applied fields, and mesoscale magnetic textures likely in the form of Ne9el-type cycloids.

Contribution

First comprehensive analysis of EuPtSi₃'s magnetic phases, textures, and anisotropy using multiple experimental techniques and neutron diffraction.

Findings

Antiferromagnetic order established below 17 K.

Multiple magnetic phases with field-dependent transitions.

Identification of mesoscale magnetic textures as Ne9el-type cycloids.

Abstract

We report a comprehensive study of single crystals of the noncentrosymmetric rare-earth compound EuPtSi$_{3}$ grown by the optical floating-zone technique. Measurements of the magnetization, ac susceptibility, and specific heat consistently establish antiferromagnetic order of localized Eu$^{2+}$ moments below the N\'{e}el temperature $T_{\mathrm{N}} = 17~\mathrm{K}$, followed by a second magnetic transition at $T_{\mathrm{N1}} = 16~\mathrm{K}$. For a magnetic field along the easy $[001]$ axis, the magnetic phase diagram is composed of these two phases. For fields applied in the magnetically hard basal plane, two additional phases emerge under magnetic field, where the in-plane anisotropy is weak with $[100]$ being the hardest axis. At the phase transitions, the magnetic properties exhibit hysteresis and discrepancies between differential and ac susceptibility, suggesting slow reorientation processes of mesoscale magnetic textures. Consistently, powder and single-crystal neutron diffraction in zero field identify magnetic textures that are modulated on a length scale of the order of $100~\textrm{\r{A}}$, most likely in the form of N\'{e}el-type antiferromagnetic cycloids.