Realization of linear magnetoelectric effect in the Dirac magnon system Cu3TeO6

The three-dimensional antiferromagnet ${\mathrm{Cu}}_{3}{\mathrm{TeO}}_{6}$ has recently drawn significant attention due to the coexistence of Dirac and triply degenerated magnons. Herein, we report that ${\mathrm{Cu}}_{3}{\mathrm{TeO}}_{6}$, with cubic symmetry, exhibits novel spin-driven ferroelectric polarization ($P$) with a strong linear magnetoelectric (ME) coupling effect by comprehensive measurements in magnetization and electric polarization. The magnetic field ($H$)-induced polarization along x-, y-, and $z$-axes emerges below ${T}_{\mathrm{N}}\ensuremath{\sim}61\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, indicative of intrinsic coupling between magnetism and ferroelectricity in this cubic lattice. Our results reveal nine nonvanished components of a ME tensor, while only the ${P}_{x} (H//z), {P}_{y} (H//x)$, and ${P}_{z} (H//y)$ components display a remarkable linear response to $H$. In particular, we observe six ME states---namely, $(\ifmmode\pm\else\textpm\fi{}{P}_{x},\phantom{\rule{0.28em}{0ex}}\ifmmode\pm\else\textpm\fi{}{M}_{z}), (\ifmmode\pm\else\textpm\fi{}{P}_{y},\phantom{\rule{0.28em}{0ex}}\ifmmode\pm\else\textpm\fi{}{M}_{x})$, and $(\ifmmode\pm\else\textpm\fi{}{P}_{z},\phantom{\rule{0.16em}{0ex}}\ifmmode\pm\else\textpm\fi{}{M}_{y})$---that can be generated by applying an external magnetic field in a specific direction, and thus makes ${\mathrm{Cu}}_{3}{\mathrm{TeO}}_{6}$ a very appealing prototype in multifunctional applications. Our results point toward ${\mathrm{Cu}}_{3}{\mathrm{TeO}}_{6}$ as a new, linear ME material and may pave a way to exploring the rich ME response in the presence of a Dirac magnon in a highly symmetric crystal structure.