Tuning the interfacial Dzyaloshinskii–Moriya interaction in perpendicularly magnetized CoFeB system

Abstract

Magnetic field driven domain-wall motion in the creep regime is investigated with Kerr microscopy in out-of-plane magnetized as deposited and annealed Ta/Pt/CoFeB/Pt multilayers. In addition to the effect of thermal annealing on the quasi-static magnetic properties of Ta (3 nm)/Pt (3 nm)/CoFeB (tCoFeB nm)/Pt (2 nm) film stacks where tCoFeB = {0.72, 0.93}, the study focuses on the modified interfacial Dzyaloshinskii-Moriya interaction (iDMI) that governs the dynamics of chiral domain walls. The strength of the iDMI decreases with an increase in both tCoFeB at a fixed annealing temperature and annealing temperature for a fixed tCoFeB. While the former behaviour arises due to the interfacial nature of iDMI, the latter correlates with the annealing induced suppression of magnetization and enhancement of interface roughness that could be respectively ascribed to B-segregation and Co-Fe-Pt intermixing.