The microstructure and magnetic properties of cobalt-rich Co-Pt alloy thin films grown using ion-beam-assisted deposition

Abstract

This study investigates the magnetic and microstructural properties of thin films (x = 0.20 and 0.25) grown by ion-beam-assisted magnetron-sputtering deposition with ion beam energies up to 500 eV. The hysteresis behaviour, particularly the coercivity, changes dramatically with the ion-beam energy (IBE). The in-plane coercivity rises sharply up to eV and drops thereafter. The c axis leaves the film plane with increasing IBE and eventually aligns normal to the film plane for films deposited at 500 eV. Detailed microstructural investigations reveal that co-bombarding the film during growth leads to the evolution of a faulted microstructure. High-resolution TEM results show that the defect structure consists of FCC lamellae slipped along the close-packed (111) planes. The faulted regions may provide pinning sites for the wall motion during magnetization reversal, thus leading to an enhancement of the coercivity.