Characterization of interlayer coupling in YIG/Py bilayer using polarized neutron reflectometry

The complex interplay of magnetic interactions at the yttrium iron garnet (YIG)/ferromagnet interface is important for spintronic and magnonic devices. In this study, we present a comprehensive investigation of the interlayer coupling and switching mechanisms in YIG/Py (permalloy) heterostructures based on gadolinium gallium garnet (GGG) and SiO₂ substrates. We observe antiferromagnetic interlayer coupling between Py and YIG on SiO₂ substrates, whereas ferromagnetic interlayer coupling is observed on GGG substrates. Using polarized neutron reflectometry with depth- and element-resolved measurements, we obtain an in-depth understanding of the magnetic interactions between the YIG and Py layers. We demonstrate that polycrystalline YIG gives rise to antiferromagnetic interlayer coupling. This work provides valuable insights into designing and controlling magnetic coupling in hybrid structures for spintronic applications.