  Changing the interlayer exchange coupling between magnetic layers in-situ is
a key issue of spintronics, as it allows for the optimization of properties
that are desirable for applications, including magnetic sensing and memory. In
this paper, we utilize the phase change material VO2 as a spacer layer to
regulate the interlayer exchange coupling between ferromagnetic layers with
perpendicular magnetic anisotropy. The successful growth of ultra-thin (several
nanometres) VO2 films is realized by sputtering at room temperature, which
further enables the fabrication of [Pt/Co]2/VO2/[Co/Pt]2 multilayers with
distinct interfaces. Such a magnetic multilayer exhibits an evolution from
antiferromagnetic coupling to ferromagnetic coupling as the VO2 undergoes a
phase change. The underlying mechanism originates from the change in the
electronic structure of the spacer layer from an insulating to a metallic
state. As a demonstration of phase change spintronics, this work may reveal the
great potential of material innovations for next-generation spintronics.
