We studied the effects of MgO and MgO/Pd seed-layers on perpendicular magnetic anisotropy in co-sputtered CoPd films. CoPd films with the MgO seed-layer showed perpendicular magnetic properties that were superior to those with another after annealing. The loop squareness was unity, indicating strong perpendicular magnetic anisotropy, when the MgO seed-layer was thicker than 2 nm. We observed that the out-of-plane CoPd (111) texture was strongly developed, as well as the in-plane tensile stress in the CoPd films. The magnetoelastic anisotropy coming from a negative magnetostriction λ111 under the in-plane tensile stress dominating over other anisotropies is likely responsible for creating such strong perpendicular magnetic anisotropy. In the case of the MgO/Pd seed-layer, the CoPd films showed mixed anisotropy having both in-plane and out-of-plane magnetic anisotropy components after annealing. The appearance of the strong (100) texture of the CoPd films with the MgO/Pd seed-layer is believed to have caused the decrease in the perpendicular magnetic anisotropy that originated from the magnetoelastic anisotropy due to the additional contribution from the positive magnetostriction λ 100 but less contribution from the negative magnetostriction λ111 when the CoPd films are under in-plane tensile stress.
Bibliographical noteFunding Information:
This research was supported in part by Basic Science Research Program through the National Research Foundation ( 2010-0015924 ) and Grant from the Center for Nanoscale Mechatronics & Manufacturing , one of the 21st Century Frontier Research Programs ( 2010K000189 ) funded by the Ministry of Education, Science and Technology in Korea, and by the IT R&D program of MKE/KEIT ( KI002189 , Technology Development of 30 nm Level High Density Perpendicular STT-MRAM).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry