Tuning Magnetic Transition Temperatures and Magnetic Entropy Change in Ferrimagnetic GdFeCo Thin Films with Perpendicular Magnetic Anisotropy

The magnetic phase transitions, perpendicular anisotropy, and magnetocaloric properties of amorphous GdFeCo ferrimagnetic thin films deposited with RF magnetron sputtering have been investigated in a wide temperature range by varying sputtering power. Magnetization and Hall effect studies of the Ta/Gd₂₄Fe₆₈Co₈/Ta multilayer structure reveal perpendicular magnetic anisotropy. A significant variation in magnetic ordering temperatures is noticed with a change in sputtering power. The Curie temperature (T_c) is found to increase from 476 to 488 K with increasing sputtering power from 50 to 70 W in the CoFe-rich phase. However, the Curie temperature decreases from 550 to 476 K with an increase in sputtering power from 80 to 100 W in the Gd-rich phase. The change in magnetic entropy rises substantially from 0.216 J/kgK for 50 W doubled to 0.4 J/kgK for a 90 W film with the application of 15 kOe field. These findings demonstrate that the sputtering power could be utilized to modulate the Curie temperature, perpendicular anisotropy, and magnetocaloric properties of amorphous ferrimagnetic thin films for multifunctional applications.