engleski

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

We report on magnetic properties of an insulating cubic compound Cu3TeO6 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 Cu2+ S=1/2 spins is present in Cu3TeO6. The magnetic susceptibility in the paramagnetic state obeys Curie-Weiss law in the 200-330 K regime with CW = &#8722; 148 K and at TN = 61 K system undergoes an antiferromagnetic phase transition. Above TN susceptibility is isotropic. Below TN a large anisotropy develops in fields H &#8805; 500 Oe. Torque measurements reveal the presence of antiferromagnetic domains below TN. In a rather low magnetic field (<500 Oe) the switching of domains is observed. The dynamics connected to movement of domain walls is very slow at low temperatures (of the order of 102 seconds) 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 wave vector k=(0, 0, 0). The dominant component of the magnetic moment is along one of the < 1&plusmn ; ; ; ; 1&plusmn ; ; ; ; 1 > space diagonals of the cubic unit cell, but it is not possible to resolve whether the structure is collinear or canted.

Saturation moments and magnetic susceptibilities; Magnetic anisotropy

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