First-principles calculations of the magnetic anisotropic constants of Co–Pd multilayers: Effect of stacking faults

¹ Institute of High Performance Computing, Agency for Science, Technology and Research - 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632
² Data Storage Institute, Agency for Science, Technology and Research - DSI Building, 5 Engineering Drive 1, Singapore 117608

^a wugaxp@gmail.com
^b ganck@ihpc.a-star.edu.sg

Received: 27 May 2012
Accepted: 11 June 2012

Abstract

Using first-principles density functional theory calculations with spin-orbit coupling, we systematically investigate the magnetic anisotropic energy (MAE) of Co_nPd_m (n+m=5) magnetic multilayers. We consider the influences of the relative atomic weight of Co, w_Co, stacking fault, and external stress on the MAE. We find that out-of-plane lattice constant, saturation magnetization, and magnetic moments are almost linearly correlated with w_Co. The magnetic anisotropic constant (MAC) curve of Co_nPd_m without stacking fault shows a near-linear dependence on w_Co that agrees with our derived effective MAC K_u^eff which includes shape, magneto-crystalline, and magneto-elastic contributions. We also show that the contributions from Pd layers to both the total magnetic moments and magnetic anisotropy are significant. The stress anisotropy due to the substrate has a weak effect on the MAC. However the stacking fault has a strong effect on the MAC. When the Co layer is thin, a Co–Pd interface without stacking fault is necessary for higher K_u^eff. However, when the Co layer is thick, creating stacking faults inside the Co region may produce a larger K_u^eff. Our study suggests the ways to increase the perpendicular magnetic anisotropy in Co–Pd multilayer systems and subsequently leads to the development of novel magnetic recording devices.