Excitation and detection of spin waves in rare-earth garnet insulator TmIG films using diamond nitrogen vacancy magnetometry

Study of spin waves, elementary excitations in magnetic materials, can be used as signal carriers in next generation electronic devices [1]. Charge as degree of freedom in devices rather than electron for transferring and representing information eliminates heating effect due to current. Among the currently available techniques, we use ferromagnetic resonance (FMR) detection method to understand the magnetization dynamics, measure the damping, and detect magnon modes in ferrimagnetic insulator Thulium iron garnet (TmIG) films (thickness of 2 -35 nm) made by pulsed laser deposition on gadolinium-gallium-garnet (GGG) substrates. We further use nitrogen-vacancy (NV) center in diamond based magnetometry to measure surface propagating spin waves at the sub-micron scale, seen by the amplification of the local microwave magnetic field due to coupling of NV spin with stray-field produced by the spin waves. We discuss the effects of thickness and substrate (sGGGs vs GGG) on the spin waves properties [2] and outline future experiments on the transport of spin waves and the mechanisms of NV-magnon coupling in TmIG nanostructures, relevant for quantum magnonic applications. [1] A. V. Chumak, et al., Nature Physics 11, 453–461 (2015), [2] R. Timalsina, et al., under preparation.