Cu substituted CeCo5: New optimal permanent magnetic material with reduced criticality
A comprehensive theoretical prediction using a mechanism of site substitution confirms the crucial role of Cu in enhancing the capabilities of CeCo5 as a competitive magnet with its known high coercivity. A remarkable enhancement of magnetic anisotropy energy (MAE) of 3.09 meV/f.u. and 2.94 meV/f.u. without significant decrease of magnetic moment is found for 10% and 5% Cu substitution at 2c sites of the hexagonal lattice. Calculations predict the increment of coercivity and magnetocrystalline anisotropy (1.6 times) compared to pristine CeCo5. The exceptional enhancement in MAE is due to the formation of asymmetric charge hybridization among the Cu (2c) and Co (both 2c and 3g) sites along the uniaxial direction. Because of this asymmetric charge distribution environment, the intrinsic behavior of Ce adjacent to Cu changes abruptly making them more uniaxial and magnetically enhanced creating mixed valence states. For these calculations, we have employed the full-potential augmented plane wave method in conjunction with spin orbit coupling.