Single-crystal growth and magnetic, magnetoelectric, and optical properties of ferroaxial-type SrMn$_2$Ni$_6$Te$_3$O$_{18}$

TL;DR

This study reports the growth and comprehensive analysis of SrMn₂Ni₆Te₃O₁₈ single crystals, revealing their magnetic, magnetoelectric, and optical properties, including domain formation and antiferromagnetic ordering at 83 K.

Contribution

First systematic investigation of ferroaxial-type SrMn₂Ni₆Te₃O₁₈ crystals, demonstrating their structural, magnetic, and magnetoelectric behaviors and domain characteristics.

Findings

Antiferromagnetic order at 83 K with c-axis collinear structure.

Detection of all allowed magnetoelectric tensor components.

Temperature-dependent anomaly and sign reversal in χ₃₃ component.

Abstract

Single crystals of SrMn$_2$Ni$_6$Te$_3$O$_{18}$, a member of the ferroaxial-type magnetic oxide family $AB_{2}C_{6}$Te$_3$O$_{18}$ ($A$ = Pb, Sr; $B$ = Mn, Cd; $C$ = Ni, Co), have been successfully grown, and their structural, magnetic, magnetoelectric, and optical properties have been systematically studied. Imaging of the spatial distribution of electric-field-induced optical rotation reveals that the single crystals preferentially form single ferroaxial (FA) domains. Magnetization and neutron diffraction measurements show that Mn$^{2+}$ and Ni$^{2+}$ magnetic moments order antiferromagnetically at $T_{\rm N}$ = 83 K, forming a $c$-axis collinear bidirector-type antiferromagnetic structure. All independent magnetoelectric tensor components allowed by the magnetic point group 6/$m^{\prime}$ have been detected, and the $\chi_{33}$ component exhibits a pronounced temperature-dependent anomaly, including a peak and a sign reversal. Preferential formation of single FA domains and a similar $\chi_{33}$ anomaly are also observed in the isostructural compound PbMn$_2$Ni$_6$Te$_3$O$_{18}$. These findings suggest that the ferroaxial and magnetic characteristics within this structural framework are robust against Sr-Pb replacement.