Tailoring of Creep Regime Domain Wall Dynamics in Perpendicularly Magnetized Pd/Co/Pd Trilayers

Abstract

Understanding magnetic domain wall (DW) dynamics is vital for improving the performance of heavy metal/ferromagnet based spintronic devices. Pd/Co/Pd multilayers hosting perpendicular magnetic anisotropy and interfacial Dzyaloshinskii-Moriya interaction are prototypes for high density magnetic memory devices. This work presents the creep regime DW dynamics in Pd/Co/Pd trilayers with Ta buffer layer excited by symmetric field-induced domain wall motion using Kerr microscopy. A systematic increment of DW velocity with increasing Co thickness is observed. SQUID-VSM measurements reveal that the effective anisotropy constant decreases with the Co layer, leading to an increased DW width. Kerr microscopy images confirm that the DW is becoming rougher with magnetic layer thickness because of the dominance of magnetostatic energy over the DW energy. Hard X-ray photoemission spectroscopy (HAXPES) reveals the presence of alloying at interfaces of Co/Pd. The asymmetry in magnetic circular dichroism HAXPES at the Pd 3d edge pictures the induced magnetic moment in Pd which is consistent with the larger saturation magnetization obtained from vibrating sample magnetometry. Extended X-ray absorption fine structure performed in out-of-plane and in-plane geometry shows the disordered nature of the Co local environment with the interdiffusion of Pd atoms into Co causing an asymmetry in the bonds.