The perpendicular magnetic anisotropy (PMA) and thermal stability of Ta (3.0 nm)/Cu (tCu)/[Co (0.29 nm)/Ni (0.65 nm)]N/Ta (3.0 nm) multilayers are investigated with various Cu thicknesses (tCu) and Co/Ni periodic numbers (N). A relatively thick Cu seed layer and a suitable Co/Ni repetition number benefit the PMA with larger coercivity and remanence ratio. But the magnetic hysteresis loop for the structure with N in excess of 10 exhibits a bow-tie shape due to the formation of multi-domains, which may cause a significant drop of the remanence ratio. The post-annealing experiments show that the thermal stability of PMA increases with increasing N. In addition to the intermixing of Co and Ni atoms at interfaces, we consider that the diffusion of nonmagnetic atoms into the magnetic layers is also responsible for the PMA decay with increasing annealing temperature.
|Original language||English (US)|
|Journal||Journal of Applied Physics|
|State||Published - May 7 2013|
Bibliographical noteFunding Information:
This work was supported by the National Natural Science Foundation of China (Grant Nos. 51222103, 11274113, 11074046, 51171047, and 61078030), and the National Basic Research Program of China (2009CB929201). B. Ma and Z. Zhang thank for the supports from the NSFC (Grant Nos. 51071046 and 11174056) and from the Program for New Century Excellent Talents in University (NCET-12-0132), respectively.