Novel spin lattice in Cu₃TeO₆: an antiferromagnetic order and domain dynamics

We report on the magnetic properties of an insulating cubic compound Cu 3 TeO 6 studied by ac and dc susceptibility, torque magnetometry and neutron powder diffraction. A novel three-dimensional magnetic lattice composed of almost planar regular hexagons of Cu 2+ S = 1/2 spins is present in Cu 3 TeO 6 . The magnetic susceptibility in the paramagnetic state obeys the Curie–Weiss law in the 200–330 K regime with Θ CW = −148 K and at T N = 61 K system undergoes an antiferromagnetic phase transition. Above T N the susceptibility is isotropic. Below T N a large anisotropy develops in fields H ≥500 Oe. Torque measurements reveal the presence of antiferromagnetic domains below T N . In a rather low magnetic field ( Oe) switching of domains is observed. The dynamics related to movement of domain walls is very slow at low temperatures (of the order of 10 2 s) and interferes with all torque measurements. The presence of domains is a consequence of the symmetry of the underlying magnetic lattice. Neutron powder diffraction reveals that antiferromagnetic long-range order is associated with the wavevector . The dominant component of the magnetic moment is along one of the space diagonals of the cubic unit cell, but it is not possible to resolve whether the structure is collinear or canted.