Effect of magnetic spins flipping process on the dielectric properties of α-Fe1.6Ga0.4O3 system

摘要

The α-Fe1.6Ga0.4O3 (Ga doped α-Fe2O3) sample has been stabilized in rhombohedral structure. The sample is a canted ferromagnet at 300 K and above. The spins structure starts flipping from in-plane direction to out of plane direction of the rhombohedral structure to exhibit an antiferromagnetic order below a typical temperature ～ 215 K, known as Morin transition. The magnetic and dielectric properties of α-Fe1.6Ga0.4O3 system have been discussed in the temperature range 123 K to 350 K to examine the effect of magnetic spins flipping process on dielectric properties. The dielectric constant has shown an anomalous peak at ～ 310 K, followed by a rapidly decrease of dielectric constant with temperature and becomes weakly temperature dependent below Morin transition. The temperature dependent dielectric constant is accompanied with the changes in electrical conductivity, dielectric loss and phase shift of the current with respect to applied ac voltage across the material. The magnetization and dielectric constant showed a linear relation over a wide range of temperature across the Morin transition. The dielectric constant at room temperature decreases under magnetic field, which indicates magneto-dielectric effect in the system. The signature of magneto-dielectric effect reveals a coupling between spins degrees of freedom (magnetic order) and charge degrees of freedom (electric polarization) in corundum structured non-traditional ferroelectric systems.