Spin waves, collective dynamic magnetic excitations, offer crucial insights into magnetic material properties. Rare‐earth iron garnets offer an ideal spin‐wave (SW) platform with long propagation length, short wavelength, gigahertz frequency, and applicability to magnon spintronic platforms. Of particular interest, thulium iron garnet (TmIG) has attracted huge interest recently due to its successful growth down to a few nanometers, observed topological Hall effect, and spin‐orbit torque‐induced switching effects. However, there is no direct spatial measurement of its SW properties. This work uses diamond nitrogen‐vacancy (NV) magnetometry in combination with SW electrical transmission spectroscopy to study SW transport properties in TmIG thin films. NV magnetometry allows probing spin waves at the sub‐micrometer scale, seen by the amplification of the local microwave magnetic field due to the coupling of NV spin qubits with the stray magnetic field produced by the microwave‐excited spin waves. By monitoring the NV spin resonances, the SW properties in TmIG thin films are measured as a function of the applied magnetic field, including their amplitude, decay length (≈50 µm), and wavelength (0.8–2 µm). These results pave the way for studying spin qubit‐magnon interactions in rare‐earth magnetic insulators, relevant to quantum magnonics applications.
This content will become publicly available on July 28, 2025
Rare‐earth iron garnets have distinctive spin‐wave (SW) properties such as low magnetic damping and long SW coherence length making them ideal candidates for magnonics. Among them, thulium iron garnet (TmIG) is a ferrimagnetic insulator with unique magnetic properties including perpendicular magnetic anisotropy (PMA) and topological hall effect at room temperature when grown down to a few nanometers, extending its application to magnon spintronics. Here, the SW propagation properties of TmIG films (thickness of 7–34 nm) grown on GGG and sGGG substrates are studied at room temperature. Magnetic measurements show in‐plane magnetic anisotropy for TmIG films grown on GGG and out‐of‐plane magnetic anisotropy for films grown on sGGG substrates with PMA. SW electrical transmission spectroscopy measurements on TmIG/GGG films unveil magnetostatic surface spin waves (MSSWs) propagating up to 80 µm with a SW group velocity of 2–8 km s−1. Intriguingly, these MSSWs exhibit nonreciprocal propagation, opening new applications in SW functional devices. TmIG films grown on sGGG substrates exhibit forward volume spin waves with a reciprocal propagation behavior up to 32 µm.
more » « less- Award ID(s):
- 2328822
- PAR ID:
- 10540259
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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