Effect of Annealing on Maze Domains in Topological Insulator - Magnetic Multilayer Heterostructures

Combining topological insulators with chiral magnetic multilayers offers the opportunity to greatly enhance the spin-orbit torque (SOT) driven manipulation of hosted spin textures, however this also exposes devices to the often poor temperature stability of the commonly used, Bi${}_2$X${}_3$-based (X is a chalcogenic element), topological insulator films. In this work we demonstrate through in-situ-annealing and polarised neutron reflectometry that the multilayer at a Bi${}_2$Se${}_3$ interface remains magnetically robust up to a temperature of 350 ${}^{\circ }$C: even as the Bi${}_2$Se${}_3$ epilayer structurally deteriorates. Through x-ray photoemission electron microscopy, an intermediate annealing temperature of $\sim$ 200 ${}^{\circ }$C was found to improve the domain ordering of the multilayer, allowing for field-induced skyrmion nucleation, all whilst sustaining minimal damage to the topological insulator