MnSb 2 O 6 : A Polar Magnet with a Chiral Crystal Structure

Structural and magnetic chiralities are found to coexist in a small group of materials in which they produce intriguing phenomenologies such as the recently discovered Skyrmion phases. Here, we describe a previously unknown manifestation of this interplay in ${\mathrm{MnSb}}_{2}{\mathrm{O}}_{6}$, a trigonal oxide with a chiral crystal structure. Unlike all other known cases, the ${\mathrm{MnSb}}_{2}{\mathrm{O}}_{6}$ magnetic structure is based on corotating cycloids rather than helices. The coupling to the structural chirality is provided by a magnetic axial vector, related to the so-called vector chirality. We show that this unique arrangement is the magnetic ground state of the symmetric-exchange Hamiltonian, based on ab initio theoretical calculations of the Heisenberg exchange interactions, and is stabilized by out-of-plane anisotropy. ${\mathrm{MnSb}}_{2}{\mathrm{O}}_{6}$ is predicted to be multiferroic with a unique ferroelectric switching mechanism.