Spin disorder in a stacking polytype of a layered magnet

Abstract

Strongly correlated ground states and exotic quasiparticle excitations in low-dimensional systems are central research topics in the solid-state research community. The present work develops a layered material and explores the physical properties. Single crystals of $3R\text{\ensuremath{-}}{\mathrm{Na}}_{2}\mathrm{MnTe}{\mathrm{O}}_{6}$ were synthesized via a flux method. Single-crystal x-ray diffraction and transmission electron microscopy reveal a crystal structure with ABC-type stacking and an $R\text{\ensuremath{-}}3$ space group, which establishes this material as a stacking polytype to previously reported $2H\text{\ensuremath{-}}{\mathrm{Na}}_{2}\mathrm{MnTe}{\mathrm{O}}_{6}$. Magnetic- and heat-capacity measurements demonstrate dominant antiferromagnetic interactions, the absence of long-range magnetic order down to 0.5 K, and field-dependent short-range magnetic correlations. A structural transition at $\ensuremath{\sim}23$ K observed in dielectric measurements may be related to displacements of the Na positions. Our results demonstrate that $3R\text{\ensuremath{-}}{\mathrm{Na}}_{2}\mathrm{MnTe}{\mathrm{O}}_{6}$ displays low-dimensional magnetism, disordered structure and spins, and the system displays a rich structure variety.