Complex magnetic couplings in Co3TeO6

Complex magnetic incommensurability and electronic charge transfer through the ferroelectric transition in multiferroic Co3TeO6

“…As the temperature is lowered, the system initially orders at T M1  = 26 K with a fully ICM magnetic structure, followed by a separate CM component ordering at T M2  = 19.5 K coexisting with the ICM magnetic order, a ferroelectric transition at T M3  = 18 K coupled to a change in the magnetic structures, and finally a transition at T M4  = 15 K into the magnetic ground state. We note that T M4 was defined as 16 K in our previous reports 14, 17 , while the present results reveal that this transition is better defined by 15 K, the temperature below which the k component of the ICM structure reappears. These transitions are naturally linked to the crystal geometry, where Co 3 TeO 6 crystallizes into a monoclinic symmetry with the space group C2 / c , with 36 Co ions in a chemical unit cell 9, 17 .…”

“…We note that T M4 was defined as 16 K in our previous reports 14, 17 , while the present results reveal that this transition is better defined by 15 K, the temperature below which the k component of the ICM structure reappears. These transitions are naturally linked to the crystal geometry, where Co 3 TeO 6 crystallizes into a monoclinic symmetry with the space group C2 / c , with 36 Co ions in a chemical unit cell 9, 17 . The complex crystalline structure of Co 3 TeO 6 can be viewed as being composed of six distorted Co 3 Te layers that are interconnected through O ions, forming significantly distorted corner-, edge-, and face-sharing CoO 6 octahedra and CoO 4 tetrahedra.…”

“…Their differences can be as large as 50%, which result in widely varying magnetic interactions that compete within the unit cell. The spin structure at 3 K has been reported 17 , where the Co spins in the zig-zag chains in Layer B order into a complex ICM spin arrangement (Fig. 3), with a modulation vector of q  = (0.357, 0.103, 0.087) for the magnetic propagation vector.…”

“…Single crystals of Co 3 TeO 6 were synthesized through chemical vapor transport redox reactions as described previously 14, 17 . The single crystal used in the present measurements was the same as in our previous work, and weighed 101 mg with a size of 14.1 × 2.2 × 0.9 mm 3 .…”

“…There are five crystallographically distinct Co ions that occupy two very different layered arrangements (Fig. 1) 9, 17 . One is comprised of distorted zig-zag Co-O-Co chains (marked Layer B, Fig.…”