Complex long-range magnetic ordering in the Mn-bearing dugganite Pb3TeMn3P2O14

Spin liquids, multiferroics, and doubly-chiral helical structures are just some of the exotic magnetic states found in the langasite compounds. A subclass of the langasite group, the Te6+-containing dugganites, has also shown exotic magnetism including magnetoelectric coupling, coexisting complex long-ranged ordered structures, and low-field induced magnetic transitions. Here, we present the first detailed structural study of Pb3TeMn3P2O14 as well as the first neutron scattering measurements. This material undergoes long-range magnetic ordering, similar to the multiferroic Ba3NbFe3Si2O14, at TN=6.6K, which is consistent with previous magnetization measurements. However unlike any other langasite or dugganite studied to date, we present evidence of a large, pseudohexagonal incommensurate supercell that alters the nuclear and magnetic structures away from the langasite ideal.