Current-Controlled Magnon-Magnon Coupling in an On-Chip Cavity Resonator

TL;DR

This paper demonstrates current-controlled magnon-magnon coupling in an ultrathin BiYIG film using an on-chip cavity resonator, revealing tunable hybridization and potential for reconfigurable magnonic devices.

Contribution

It introduces a novel on-chip cavity resonator system where spin currents control magnon coupling and hybridization, enabling reconfigurable magnonic functionalities.

Findings

Spin current injection suppresses cavity modes and hybridization.

Tuning microwave power adjusts the anticrossing gap.

Modeling accurately reproduces observed magnon modes.

Abstract

Harnessing spin currents to control magnon dynamics enables new functionalities in magnonic devices. Here, we demonstrate current-controlled magnon-magnon coupling between cavity and boundary modes in an ultrathin film of Bi-doped yttrium iron garnet (BiYIG). Cavity modes emerge in a BiYIG region between two Pt nanostripes, where interfacial anisotropy modifies the magnon dispersion. These modes hybridize with boundary magnons confined within the Pt-capped BiYIG, resulting in an anticrossing gap. Modeling based on dipole-exchange spin-wave dispersion accurately reproduces the observed modes and their hybridization. Spin current injection via the spin Hall effect in a Pt nanostripe disrupts the cavity boundary conditions and suppresses both cavity modes and hybridization upon driving the system beyond the damping compensation threshold. Furthermore, tuning the microwave power applied to a microstrip antenna enables controlled detuning of the anticrossing gap. Our findings provide a platform for exploring spin current-magnon interactions and designing on-chip reconfigurable magnonic devices.