Magnetic properties of single crystals of a new cobaltite TbBaCo4O7+x

The temperature and field dependences of the magnetization of a single crystal of a new class of layered cobaltites, TbBaCo4O7+x, with a structure containing a Kagomé lattice and a triangular lattice were measured. The measurements were performed on a SQUID magnetometer at temperatures in the range 2–300 K and in magnetic fields of up to 55 kOe for two field orientations. The anisotropy of the magnetization was studied, and the presence of antiferromagnetic ordering in fields H < Hc and a weak magnetic-field-induced (H > Hc) ferromagnetic component in the low-temperature range was demonstrated. The magnetic characteristics of the initial TbBaCo4O7+x single crystal and the single crystal annealed in an O2 atmosphere were compared.