Role of CoFeB/Pt stacking order on interfacial Dzyaloshinskii–Moriya interaction driven spin-wave asymmetry

Abstract

The interfacial Dzyaloshinskii–Moriya interaction (iDMI) plays a vital role in stabilizing chiral magnetic textures and enabling nonreciprocal spin-wave propagation, both of which are essential for the development of next-generation spintronic devices. Controlling iDMI through material design and interface engineering is therefore important for achieving more energy-efficient information technologies. CoFeB/Pt heterostructures are particularly versatile due to their adjustable magnetic and spin–orbit properties. In this study, we examine how stacking sequence, interface quality, and magnetic moment density influence iDMI in CoFeB/Pt thin films using magnetometry and Brillouin light scattering. We find that changing the layer order, creating symmetric stacks, or inserting spacer layers significantly alters spin-wave nonreciprocity. Notably, the frequency shift when CoFeB is deposited on top of Pt is more than twice, and the iDMI constant is almost four times higher than that when Pt is on top of the CoFeB; the effects related to ferromagnet thickness and moment density confirm that the origin is at the interface. These findings offer practical insights into interface engineering for tunable chiral spin dynamics in ultrathin magnetic films.