Design and micromagnetic simulation of the <i>L</i>1-FePt/Fe multilayer graded film

Abstract

The magnetic properties of the L10-FePt20 nm/Fe5 nm exchange spring bilayer were investigated using the micromagnetic simulation software object oriented micromagnetic framework (OOMMF). The results indicate that coercivity increases and thermal stability improves as the magnetocrystalline anisotropy constant (KFePt) of the L10-FePt hard layer increases. When KFePt reaches the critical value of 2.8 × 106 J/m3, an additional step appears in the hysteresis loop, and the magnetization process shows a two-phase reversal behavior, which is disadvantageous for practical applications of the recording media. However, setting KFePt as a graded variation removes the step of the hysteresis loop and reduces coercivity while allowing the thermal stability of the system to remain constant. These results can serve as a significant basis for the experimental preparation of exchange-coupled graded media.