Conical incommensurate magnetic ordering in the transition metal-rich YCo12B6 ternary boride

The ternary boride YCo 12 B 6 was investigated by means of ac susceptibility, magnetization, and neutron powder diffraction experiments over the temperature range 1.5–300 K. The crystal structure was refined and the spin configuration determined. This intermetallic compound crystalizes in a rhombohedral R 3 ¯ m structure. In the ground state, its magnetic structure is characterized by a short incommensurate propagation vector k = (0, 0, ± 0.0432), i.e., a long incommensurate period along the c -axis. Substantially different magnetic moments have been observed on the two crystallographically inequivalent Co sites (18 g and 18 h ), a larger moment being refined on the Co-18 h position. The Co spins arrange themselves into a conical magnetic structure with a tilt angle of about 57° with respect to the threefold symmetry axis c . Furthermore, a highly anisotropic lattice expansion is observed. • Neutron powder diffraction. • Long incommensurate period along the c -axis. • Spin conical modulations. • Highly anisotropic lattice expansion.