Investigation and Effective Control of Perpendicular Magnetic Anisotropy for TbCo Films with Different Underlayers

We performed a detailed study on the perpendicular magnetic anisotropy (PMA) of TbCo film by using two kinds of nonmagnetic underlayers, Ta and Ta/Cu with different thicknesses. We found that for both the Tb-rich and Co-rich TbCo alloy films, the PMA strength decreases considerably with the increase of Ta underlayer thickness, while their net saturation magnetization M _s exhibit opposite varying trends. The M _s value continues to increase for the Co-rich TbCo samples while decrease for the Tb-rich films. Interestingly, an additional Cu layer inserted between the Ta and TbCo layers can effciently recover the PMA and M _s . We attribute such observed variation behaviors of magnetic properties to the increased disordering of Tb magnetic moments at the Ta/TbCo interface, which has been verified by both experimental measurements and micromagnetic simulations.