Magnetic Structure of the $S\,{=}\,1/2$ Quasi-Two-Dimensional Square-Lattice Heisenberg Antiferromagnet Sr$_2$CuTeO$_6$

TL;DR

This study elucidates the magnetic structure of Sr$_2$CuTeO$_6$, revealing a Neel antiferromagnetic order consistent with dominant nearest-neighbor interactions, contrasting with similar compounds.

Contribution

First neutron diffraction study of Sr$_2$CuTeO$_6$ establishing its magnetic structure and interaction hierarchy in the quasi-2D square-lattice Heisenberg model.

Findings

Neel antiferromagnetic order below 29 K

Nearest-neighbor interaction ($J_1$) is stronger than next-nearest ($J_2$)

Contrasts with isostructural compounds like Ba$_2$CuWO$_6$

Abstract

The magnetic structure of the double perovskite compound Sr$_2$CuTeO$_6$ was determined from neutron powder diffraction data. This material is magnetically described as an $S\,{=}\,1/2$ quasi-two-dimensional square-lattice Heisenberg model with antiferromagnetic nearest-neighbor and next-nearest-neighbor interactions. Sr$_2$CuTeO$_6$ undergoes a magnetic phase transition at $T_{\rm N}\,{\simeq}\,29\,$ K. The spin structure below $T_{\rm N}$ is N\'{e}el antiferromagnetic on the square lattice, which means that the nearest-neighbor interaction ($J_1$) is stronger than the next-nearest-neighbor interaction ($J_2$), in contrast to other isostructural compounds such as Ba$_2$CuWO$_6$ and Sr$_2$CuWO$_6$, for which $|J_1|\,{<}\,|J_2|$ is realized.