Manipulation of coupling and magnon transport in magnetic metal-insulator hybrid structures

Abstract

Ferromagnetic metals and insulators are widely used for generation, control, and detection of magnon spin signals. Most magnonic structures are based primarily on either magnetic insulators or ferromagnetic metals, while heterostructures integrating both are less explored. Here, by introducing a Pt/yttrium iron garnet (YIG)/permalloy (Py) hybrid structure grown on Si substrate, we studied the magnetic coupling and magnon transmission across the interface of the two magnetic layers [1]. Interestingly, we found the YIG and the Py layers show antiferromagnetic coupling when external field is small, and the two layers align to the same direction only when the in-pane field is above 150 mT, as evidenced by both vibrating-sample magnetometry and polarized neutron reflectometry measurements. More importantly, the parallel and antiparallel magnetization configurations in this YIG/Py structure could be utilized to control magnon spin flow in spin-pumping and spin Seebeck experiments. In Figure 1(a) and 1(b), we schematically illustrate the effect of magnetization configuration (antiparallel vs parallel) on the magnon current transmission efficiency across the two magnetic layers’ interface. In the spin-pumping experiment, as plotted in Figure 1(c), we demonstrate that a magnon spin-valve device with an ON/OFF ratio of ~130% can be realized out of this multilayer structure at room temperature. Owing to the efficient control of magnon current and the compatibility with Si technology, the Pt/YIG/Py hybrid structure could potentially find applications in magnon-based logic and memory devices.