Perpendicular magnetic anisotropy of Pd/Co₂MnSi/NiFe₂O₄/Pd multilayers on F-mica substrates

Pd/Co₂MnSi (CMS)/NiFe₂O₄ (NFO)/Pd multilayers were fabricated on F-mica substrate by magnetron sputtering. The best PMA performance of the multilayer structure Pd(3 nm)/CMS(5 nm)/NFO(0.8 nm)/Pd(3 nm) was obtained by adjusting the thickness of the CMS and NFO layers. F-mica substrate has a flatter surface than glass and Si/SiO₂ substrate. The magnetic anisotropy energy density (K_eff) of the sample deposited on F-mica substrates is 0.6711 Merg/cm³ (1 erg = 10^-7 J), which is about 30% higher than that of the multilayer films deposited on glass (0.475 Merg/cm³) and Si/SiO₂ (0.511 Merg/cm³) substrates, and the R_Hall and H_C are also significantly increased. In this study, the NFO layer prepared by sputtering in the high purity Ar environment was exposed to the high purity O₂ atmosphere for 5 min, which can effectively eliminate the oxygen loss and oxygen vacancy in NFO, ensuring enough Co-O orbital hybridization at the interface of CMS/NFO, and thus effectively improve the sample PMA.