Electric current induced coercivity change in Co/Pd multilayer thin films

Abstract

In this work, we present the experimental results on the effect of electric current-induced diffusion leading to change in ferromagnetic behavior of Co/Pd multilayer thin films. We applied high-density direct current to a Co/Pd multilayer specimen in ambient conditions. We observed an almost 8.8 times change in coercivity and improved squareness of the thin films using magneto-optic Kerr effect measurement. Magnetic force microscope studies further validate an increase in the coercivity for the current-treated thin films. We experimentally observe that this change cannot be attributed only to Joule heating due to electric current. We propose that the underlying mechanism for the observed behavior is electromigration induced diffusion along the grain boundaries and the thin film surface. Surface diffusion of O2 leads to formation of CoO resulting in the permanent coercivity change observed in this work. The composition of the specimens is Ta (1 nm)/ [Co (0.35 nm)/Pd (0.55 nm)]20.

Spin-orbit torque induced reversible coercivity change in Co/Pd multilayer thin films

“…The curie temperature of multilayer structures has been found to be between 300°C and 400°C [26]. The thin films used in the current study has been found to loose the magnetic behavior irreversibly above 300°C [27].…”

The dominancy of damping like torque for the current induced magnetization switching in Pt/Co/W multilayers

“…Currently, most studies have focused on SOT in ultrathin FMs sandwiched between two HM layers, such as Pt/CoNiCo/Pt, Pt/Co/Ta, Pt/Co-Ni/W, and Pt/Co/Pt [18][19][20][21][22][23], in which both of the HM layers have contributions to the spin accumulation at the interfaces. Because the efficiency of SOT relates directly to the magnitude of effective spin Hall angle ( SH ), it is considered that the overall  SH will be enhanced if the sign of  SH in the top and bottom HM layer is opposite.…”