Evidence for cluster spin-glass like phase with longitudinal conical magnetic structure in Ga doped M-type barium hexaferrite, BaFe10Ga2O19

Abstract A systematic study of structure and magnetic properties of the gallium doped M-type barium hexaferrite BaFe10Ga2O19 using dc magnetization and ac susceptibility, magnetic relaxation, heat capacity, neutron diffraction and Raman spectroscopy is presented. dc magnetization, ac susceptibility and magnetic relaxation measurements show the presence of cluster glass-like behaviour below spin reorientation transition temperature, TSRT ~ 120 K. Temperature dependent neutron diffraction studies indicate the presence of longitudinal conical magnetic structure below TSRT, where the cones make an angle α = 24.53° with the c-axis. Below TSRT, due to coexistence of the two magnetic states (cluster glass-like and longitudinal conical magnetic structure), a small exchange bias field, HEB = 48.47 Oe is also observed in this system. Changes in the lattice parameters (a and c), deviation from the Debye-Gruneisen equation in the volume versus temperature plot and changes in the Raman phonon modes around TSRT confirm the presence of spin lattice coupling in this system.