ИСТИНА

We report on the static and dynamic magnetic properties of two polymorphs of the triangular lattice antiferromagnet MnSb2O6, which are characterized by two different layered trigonal crystal structures: space groups (P321) and (P31m) respectively. Based on neutron powder diffraction data and DFT calculations, the first one (P321 form) has been recently predicted to be multiferroic with a unique ferroelectric switching mechanism [1]. However, no systematic experimental studies of its magnetic properties have been performed up to now. The second polymorph under study (P31m form) was synthesized and investigated for the first time. It was found that both compounds exhibit long-range antiferromagnetic order with Neel temperatures TN ~ 12 K for (P321) form and TN ~ 8.5 K for (P31m) form, respectively. The Weiss temperatures are negative indicating predominance of antiferromagnetic interactions. The effective magnetic moment for both compounds is about 5.9(2) B/f.u., which agrees well with theoretical estimations using the measured effective g-factors and assuming high-spin configuration of Mn2+. The magnetization curves exhibit the presence of magnetic field induced spin-flop transitions at BC~1 T for (P321) form and BC~0.7 T for (P31m) form, respectively. In addition, there is a weak ferromagnetic component detected in the magnetic susceptibility below T1 = 41.5(5) K for the (P31m) sample. Both low field (X-band) and high field ESR studies corroborate the static magnetization data and reveal non trivial spin dynamics in the (P31m) form. In consistence with our experimental findings, the magnetic phase diagrams have been constructed for both compounds.